refactor(tools): group the sixty scripts by what they talk to

One directory with sixty scripts stopped being navigable, and the grouping is also the sandbox boundary:

  Tools/unreal/    commandlets and the two map builders, with ue_common.py and ue_placement.py as the
                   shared imports (they need the engine)
  Tools/blender/   builders, exporters, the FBX preset, the MPFB character pipeline, blender_screenshots
                   (they need the Blender Flatpak)
  Tools/review/    the visual loop: render_screenshots.sh, judge_screenshot.py, hero_compare.py,
                   build_comparison_md.py, e2e_asset_check.py, hero_iterate.sh, visual_loop.py,
                   visual_targets.json
  Tools/gen/       image and texture generation: the ComfyUI driver, deterministic texture writers,
                   reference fetching
  Tools/input/     OS-level input injection
  root             _common.py, check-lfs.sh, addon_compat_probe.py, sibling_asset_audit.py, tests/

Every moved script now resolves the repository root as ../.. and puts the tools root plus its siblings on
sys.path, so 'import ue_common' still works from unreal/. The test suite bootstrap does the same for the five
folders. render_screenshots.sh takes the folder as a third argument to run_cmdlet, and the e2e driver,
hero_iterate.sh and the comparison generator were repointed.

51 README rows now link to their new location, the README gains a Layout section naming each folder's
sandbox, and the architecture notes and Blender README follow the moves.

Verified: 108 tests pass, prettier is clean, judge_screenshot.py and hero_compare.py run from their new
homes, and the e2e run was aborted mid-way (it had been rebuilding an empty DemoMap for 15 minutes) and is
being rerun against the new layout.

CHANGELOG.md

@@ -38,12 +38,12 @@ The character becomes a character: clothed, haired, and measured against a gener
 
 ### Added
 
-- **Clothing** — navy tee, dark jeans and off-white shoes as three separate skinned meshes (`Tools/character_clothing_build.py`), built from the body's own faces per the `character-artist` workflow: duplicate faces, solidify for cloth thickness, one mesh per piece. Each imports with its own single material slot and is attached as a leader-pose component.
-- **Hair cards** (`Tools/character_hair_build.py`) — a scalp cap plus 26 cards in three overlapping rows, quads only, every vertex weighted to `head`. Cards are oriented from the scalp normal at their anchor, so the cut follows the skull instead of standing out as spikes.
-- **Character blueprints** (`Tools/comfyui_character_blueprint.py`) — front, side, back and head views generated by the local ComfyUI instance from one description, with fixed seeds and a JSON record of prompts and prompt ids.
-- **Blueprint comparison** (`Tools/character_match.py`) — figure aspect, fill and coverage deltas, mean CIE76 and dominant-palette distance, plus a side-by-side montage. The deltas stay separate on purpose: one similarity number between a photoreal sheet and a low-detail body would mean nothing.
-- **ComfyUI driver** (`Tools/comfyui_generate.py`) and **procedural textures** (`Tools/generate_character_textures.py`), each writing a provenance sidecar.
-- **Material builder** (`Tools/ue_character_materials.py`) — `M_Character_Skin` and `M_Character_Hair_Mat` built from scratch, because `unreal.MaterialEditingLibrary` segfaults in a headless commandlet when it rebuilds an existing graph.
+- **Clothing** — navy tee, dark jeans and off-white shoes as three separate skinned meshes (`Tools/blender/character_clothing_build.py`), built from the body's own faces per the `character-artist` workflow: duplicate faces, solidify for cloth thickness, one mesh per piece. Each imports with its own single material slot and is attached as a leader-pose component.
+- **Hair cards** (`Tools/blender/character_hair_build.py`) — a scalp cap plus 26 cards in three overlapping rows, quads only, every vertex weighted to `head`. Cards are oriented from the scalp normal at their anchor, so the cut follows the skull instead of standing out as spikes.
+- **Character blueprints** (`Tools/blender/comfyui_character_blueprint.py`) — front, side, back and head views generated by the local ComfyUI instance from one description, with fixed seeds and a JSON record of prompts and prompt ids.
+- **Blueprint comparison** (`Tools/blender/character_match.py`) — figure aspect, fill and coverage deltas, mean CIE76 and dominant-palette distance, plus a side-by-side montage. The deltas stay separate on purpose: one similarity number between a photoreal sheet and a low-detail body would mean nothing.
+- **ComfyUI driver** (`Tools/gen/comfyui_generate.py`) and **procedural textures** (`Tools/gen/generate_character_textures.py`), each writing a provenance sidecar.
+- **Material builder** (`Tools/unreal/ue_character_materials.py`) — `M_Character_Skin` and `M_Character_Hair_Mat` built from scratch, because `unreal.MaterialEditingLibrary` segfaults in a headless commandlet when it rebuilds an existing graph.
 
 ### Changed
 
@@ -92,7 +92,7 @@ Third-person body. The pawn gains a visible, animated body and a third-person ca
 
 ### Added
 
-- **`Tools/character_anim_build.py`**: `GigLine_Idle` (60 frames) and `GigLine_Walk` (30 frames) at 30 fps, authored as parametric cycles so the loop closes by construction. Limb axes were **measured** on the rig — a probe rotated `upperleg01.L` by 0.5 rad on each axis and read `foot.L`, which showed X swings the limb fore/aft while Y twists and Z abducts.
+- **`Tools/blender/character_anim_build.py`**: `GigLine_Idle` (60 frames) and `GigLine_Walk` (30 frames) at 30 fps, authored as parametric cycles so the loop closes by construction. Limb axes were **measured** on the rig — a probe rotated `upperleg01.L` by 0.5 rad on each axis and read `foot.L`, which showed X swings the limb fore/aft while Y twists and Z abducts.
 - **Third-person rig** (`ADR-9`): a visible skeletal body, a `USpringArmComponent` with collision testing, and a **V** toggle. One pawn carries both rigs; first person stays the shipped default.
 - **Walk capture harness**: a per-shot `ShotFollow` mode that re-places the review camera every frame in the pawn's frame, plus `SetReviewWalk` / `ReturnToStartForReview`, so a stride is captured deterministically and the fixed-camera shots still find the pawn at spawn.
 - **Review shots 6, 7 and 8** — third-person back, front and mid-stride — embedded in `Screenshots/README.md`.
@@ -130,8 +130,8 @@ Retail frontage. The two retail buildings beside the hero are modelled from thei
 
 ### Added
 
-- **`Tools/retail_frontage_build.py`**: 6800 Lee Drug and 6806–6820 built from the one usable reference (`Art/reference/retail-neighbours/`, Gb321, CC BY-SA 4.0). Lee Drug gets a bronze cornice, storefront glazing with mullions, framed portrait panels, a painted lettering band, two-tier parapet with reveals and a fluted corner tower; 6806–6820 gets a burgundy fascia, brown pilasters, white-framed windows with security bars and its own banded parapet. Built in world coordinates from the blockout bounds (Lee Drug X −33.20…−14.37, face Y −14.63, H 12.10 m; 6806–6820 X −66.08…−33.07), joined to one mesh per building with a JSON part report.
-- **`Tools/ue_import_retail_detail.py`**: imports the two meshes with complex-as-simple collision — trim decorates a solid the player already collides with and must not add snag points.
+- **`Tools/blender/retail_frontage_build.py`**: 6800 Lee Drug and 6806–6820 built from the one usable reference (`Art/reference/retail-neighbours/`, Gb321, CC BY-SA 4.0). Lee Drug gets a bronze cornice, storefront glazing with mullions, framed portrait panels, a painted lettering band, two-tier parapet with reveals and a fluted corner tower; 6806–6820 gets a burgundy fascia, brown pilasters, white-framed windows with security bars and its own banded parapet. Built in world coordinates from the blockout bounds (Lee Drug X −33.20…−14.37, face Y −14.63, H 12.10 m; 6806–6820 X −66.08…−33.07), joined to one mesh per building with a JSON part report.
+- **`Tools/unreal/ue_import_retail_detail.py`**: imports the two meshes with complex-as-simple collision — trim decorates a solid the player already collides with and must not add snag points.
 - **`Art/blender/retail/ref-analysis.md`**: the reference analysis the `references` skill pack requires, written before modelling.
 - **`Tools/_common.py`** and `Tools/tests/test_retail_frontage.py`: the bay-layout arithmetic, extracted so it is testable without Blender (4 tests).
 - **Review shot 5**, `demo/review-demo-retail-frontage`, embedded in `Screenshots/README.md`.
@@ -144,7 +144,7 @@ Retail frontage. The two retail buildings beside the hero are modelled from thei
 
 ### Fixed
 
-- **`Tools/render_screenshots.sh` never captured anything.** The capture step called `./Engine/...` while every commandlet above it went through `run_cmdlet`'s `cd "$ENGINE"`. Under `set -e` the script died at exit 127 _after_ rebuilding the maps, so the PNGs silently stayed a day old and `--verify` never ran.
+- **`Tools/review/render_screenshots.sh` never captured anything.** The capture step called `./Engine/...` while every commandlet above it went through `run_cmdlet`'s `cd "$ENGINE"`. Under `set -e` the script died at exit 127 _after_ rebuilding the maps, so the PNGs silently stayed a day old and `--verify` never ran.
 - **Duplicate `RetailTrim_*` actors on every rebuild**: the demo builder's clear list did not include the new label, so each run stacked another copy. Caught by the scene audit, not by eye.
 - **Mural plates were placed 0.20 m inside the solid blockout volume** and never rendered; the inset is now faked with a proud frame and a near-flush plate.
 - **Trim detail sat 0.05 m off the wall**, under a pixel of depth at 40 m, so the wall won the depth test. Trim planes now stand 0.10–0.20 m proud.
@@ -170,8 +170,8 @@ Façade finishing. The kit gets the hero detail it was missing, and a class of s
 
 ### Added
 
-- **Scene audit** (`Tools/ue_audit_scene.py`): fails when any staged mesh has no material, when a frontage building is more than ±1 m off its verified footprint, or when two actors share a label. Wired into `Tools/render_screenshots.sh`, which now runs the whole staging chain in the correct order and stops on an audit failure.
-- **`Tools/ue_placement.py`**: one source of truth for staged positions and the verified frontage spans, with `span_error` / `describe_span_failure` validators.
+- **Scene audit** (`Tools/unreal/ue_audit_scene.py`): fails when any staged mesh has no material, when a frontage building is more than ±1 m off its verified footprint, or when two actors share a label. Wired into `Tools/review/render_screenshots.sh`, which now runs the whole staging chain in the correct order and stops on an audit failure.
+- **`Tools/unreal/ue_placement.py`**: one source of truth for staged positions and the verified frontage spans, with `span_error` / `describe_span_failure` validators.
 - **Hero fluting**: 20 grooves per column as shallow shadow-tone cylinders (120 pieces) rather than boolean cuts.
 - **Presence of references for the retail run**: `Art/reference/retail-neighbours/` (6800 Lee Drug and its neighbour). Local only, not committed.
 
@@ -210,9 +210,9 @@ Building façades. The block goes from flat extruded boxes with flat colours to
 - **Generated surface textures** — deterministic stdlib PNGs for ashlar stone, stucco, asphalt and concrete (base colour + roughness), sampled world-aligned with per-material tiling; byte-identical on re-run.
 - **Materials**: masonry coursing and roughness variation in the material graphs; `M_FacadeStoneShadow`, `M_FacadeGlass` (specular 0.62 ≈ IOR 1.5) and `M_FacadeBanner`. Material assignment is now **per slot**, keyed on the imported slot material, instead of slot 0 only.
 - **El Capitan Theatre trim**: projecting marquee (12.0 × 2.60 m canopy at a 4.60 m soffit), illuminated fascia, recessed soffit, and a vertical blade sign (1.30 × 5.20 m) with frame and wall bracket.
-- **Visual review loop** (`Tools/visual_loop.py` + `visual_targets.json`): verifies every capture against an expectation (missing, blank, tone-less or wrong-size shots fail) and measures each render against its reference photograph, emitting feedback that names the discipline to consult. Iterations are written under `Art/reference/iterations/`, which is gitignored until a shot is confirmed.
-- **`Tools/fbx_export_preset.py`** — one export preset replacing six copies, and it exports smoothing groups (`FACE`), so round geometry is no longer faceted.
-- **`Tools/ue_common.py`** — clears the read-only bit an LFS `.umap` checks out with and makes a refused save loud.
+- **Visual review loop** (`Tools/review/visual_loop.py` + `visual_targets.json`): verifies every capture against an expectation (missing, blank, tone-less or wrong-size shots fail) and measures each render against its reference photograph, emitting feedback that names the discipline to consult. Iterations are written under `Art/reference/iterations/`, which is gitignored until a shot is confirmed.
+- **`Tools/blender/fbx_export_preset.py`** — one export preset replacing six copies, and it exports smoothing groups (`FACE`), so round geometry is no longer faceted.
+- **`Tools/unreal/ue_common.py`** — clears the read-only bit an LFS `.umap` checks out with and makes a refused save loud.
 
 ### Changed
 
@@ -249,7 +249,7 @@ Packaging and setup fixes. No gameplay or visual scope; this patch makes the pip
 
 ### Fixed
 
-- **Map imports could report success while saving nothing.** `.umap` files are LFS-tracked and check out read-only, so `save_map()` returned `False` with no error and the staged actor vanished on the next load. New `Tools/ue_common.py` (`make_writable`, `require_saved`) clears the read-only bit and makes the failure loud; `ue_hero_facade_import.py` and `ue_import_north_buildings.py` now use it. Verified from a forced `0o444` map: chmod logged, `save_map: True`, exit 0.
+- **Map imports could report success while saving nothing.** `.umap` files are LFS-tracked and check out read-only, so `save_map()` returned `False` with no error and the staged actor vanished on the next load. New `Tools/unreal/ue_common.py` (`make_writable`, `require_saved`) clears the read-only bit and makes the failure loud; `ue_hero_facade_import.py` and `ue_import_north_buildings.py` now use it. Verified from a forced `0o444` map: chmod logged, `save_map: True`, exit 0.
 
 ### Changed
 
@@ -268,8 +268,8 @@ Scale and façade correction patch. Buildings and the hero elevation now match t
 
 ### Added
 
-- **`Tools/facade_detail_concepts.py`** — generates frontal building plates (whole elevation, entrance in its façade, building with neighbours) from a local reference photograph through OpenRouter image models. Spec-driven, never overwrites, writes a provenance sidecar per image, output stays in the gitignored `Art/reference/` tree. Local working material only.
-- **`Tools/fbx_export_preset.py`** — the single FBX export preset (`ue_metric_v1` / `ue_character_v1`). Replaces the argument block that had been copied into six exporters.
+- **`Tools/gen/facade_detail_concepts.py`** — generates frontal building plates (whole elevation, entrance in its façade, building with neighbours) from a local reference photograph through OpenRouter image models. Spec-driven, never overwrites, writes a provenance sidecar per image, output stays in the gitignored `Art/reference/` tree. Local working material only.
+- **`Tools/blender/fbx_export_preset.py`** — the single FBX export preset (`ue_metric_v1` / `ue_character_v1`). Replaces the argument block that had been copied into six exporters.
 - **Façade occlusion probe** in `-qaselftest`: 40 m traces sideways from the road centre at walking height, required wherever a building is staged.
 - **Ionic detail on the hero**: base moulding at every shaft foot, a square abacus over every capital, and a 52-dentil cornice course.
 - **Tool tests**: `Tools/tests/` now covers the input driver, height classification, the Mapbox cross-check, the concept generator and the FBX preset (49 tests).
@@ -335,16 +335,16 @@ The first playable release: a walkable exterior demo of the **6840 Hollywood Blv
 
 - **Unreal project** (`Game/GigLine`) — C++ game module, Enhanced Input, packaged Linux build, and a `DemoMap` that a plain launch opens directly.
 - **Walkable demo level** — terrain from the 3DEP DEM, Hollywood Blvd carriageway, both sidewalks and kerbs with collision, the designated mid-block crossing, and fixed daytime lighting (sun, sky light, sky atmosphere, height fog, pinned exposure).
-- **Hero façade** for 6840 Hollywood Blvd — six-column neoclassical elevation with three genuine portal recesses, entablature, parapet and motto band (`Tools/hero_facade_build.py`, `Tools/ue_hero_facade_import.py`).
+- **Hero façade** for 6840 Hollywood Blvd — six-column neoclassical elevation with three genuine portal recesses, entablature, parapet and motto band (`Tools/blender/hero_facade_build.py`, `Tools/unreal/ue_hero_facade_import.py`).
 - **Block frontage** — the five verified south-side neighbours (6922, 6902, 6838 El Capitan Theatre, 6822 Budget, 6806–6822, 6800 Lee Drug) and the two north-side buildings (TCL Chinese Theatre, Madame Tussaud's) placed at their OSM positions.
 - **First-person player** — `AGigLineCharacter`: 1.75 m capsule, 1.60 m eye camera, 4 m/s walk, mouse look, jump, reset (`R`) and pause (`Escape`); controls documented in `Docs/controls.md` and shown in-game.
 - **In-game ODbL attribution** — `AGigLineHUD` draws the OpenStreetMap credit and licence line every frame.
-- **QA harness** — `-qaselftest` (walk, reset, pause, seam transect, invisible-wall probe, frame-time capture) and `Tools/input_test.py` / `Tools/input_emulation.py` for OS-level virtual keyboard/mouse input.
+- **QA harness** — `-qaselftest` (walk, reset, pause, seam transect, invisible-wall probe, frame-time capture) and `Tools/input/input_test.py` / `Tools/input/input_emulation.py` for OS-level virtual keyboard/mouse input.
 - **Documentation** — setup, build, toolchain, licensing, ODbL review, release checks, and arc42 architecture docs.
 
 ### Fixed
 
-- **All controls were dead in packaged and PIE builds.** The mapping-context generator wrote key bindings to the deprecated `mappings` array; UE 5.8 reads `DefaultKeyMappings.Mappings`, so the cooked game had zero runtime mappings and every key resolved to nothing. `Tools/ue_create_input_assets.py` now populates the current field.
+- **All controls were dead in packaged and PIE builds.** The mapping-context generator wrote key bindings to the deprecated `mappings` array; UE 5.8 reads `DefaultKeyMappings.Mappings`, so the cooked game had zero runtime mappings and every key resolved to nothing. `Tools/unreal/ue_create_input_assets.py` now populates the current field.
 - **"Fall-through" was an 8 m invisible box.** `Terrain_DEM` shipped only a bounding-box collision proxy; forcing complex-as-simple collision (`UGigLineAssetTools`) put the player on the actual street.
 - **Reset returned the player to mid-air** — the start position is now captured on the first grounded frame.
 - **Plain launch opened the engine template** — the default map now lives in `DefaultEngine.ini` and points at `DemoMap`.