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.

Docs/Architecture/04_solution_strategy.md

@@ -30,7 +30,7 @@ All modelling and geographic processing live outside the game project in `Art/`,
 
 ## Quality achievement
 
-- **Realism first**: reference photography and measured data drive every façade decision; renders are compared against the photographs with `Tools/visual_loop.py`, and a façade is built from the shared 4.96 m module kit so the street wall reads consistently. Materials are authored in Unreal with world-aligned generated textures, and lighting is fixed daytime so a shot is comparable between runs.
+- **Realism first**: reference photography and measured data drive every façade decision; renders are compared against the photographs with `Tools/review/visual_loop.py`, and a façade is built from the shared 4.96 m module kit so the street wall reads consistently. Materials are authored in Unreal with world-aligned generated textures, and lighting is fixed daytime so a shot is comparable between runs.
 - **Performance as a budget, not a driver**: dynamic-only lighting (no build step, no static shadow maps), world-space-noise materials (cheap procedural variation), minimal overdraw for street-level geometry, and a 60 FPS at 1440p floor that every release must meet. It closes the quality list because it constrains how much realism fits, not what the block should look like.
 
 - **Walkability**: complex-as-simple collision on terrain (C++ helper forces the flag on the asset), block-all collision on every site mesh, swept transect QA verifies zero raycast holes.

Docs/Architecture/05_building_block_view.md

@@ -49,7 +49,7 @@ Static meshes and materials in `/Game/Hollywood/Site/`:
 | `SM_HeroFacade` | El Capitan Entertainment Centre detailed façade |
 | `SM_ElCapitanTheatre`, `SM_Budget_6822`, `SM_Hollywood_6806`, `SM_Hollywood_6902`, `SM_Hollywood_6922`, `SM_LeeDrug_6800` | South block frontage (6 buildings) |
 | `SM_Madame_Tussauds`, `SM_TCL_Chinese_Theatre` | North-side buildings (within 50 m) |
-| `SM_Retail_LeeDrug`, `SM_Retail_6806` | Retail trim over 6800 and 6806–6820, modelled from their own photograph (`Tools/retail_frontage_build.py`, staged as `RetailTrim_*`). `6822 Budget` stays a bare volume: no photograph exists. |
+| `SM_Retail_LeeDrug`, `SM_Retail_6806` | Retail trim over 6800 and 6806–6820, modelled from their own photograph (`Tools/blender/retail_frontage_build.py`, staged as `RetailTrim_*`). `6822 Budget` stays a bare volume: no photograph exists. |
 
 ### Art Pipeline
 

Docs/Architecture/06_runtime_view.md

@@ -18,7 +18,7 @@
 
 ## Screenshot capture
 
-1.  `Tools/render_screenshots.sh` compiles editor, builds `ReviewMap` from `Tools/ue_build_review_map.py`, launches game in `-game` mode.
+1.  `Tools/review/render_screenshots.sh` compiles editor, builds `ReviewMap` from `Tools/unreal/ue_build_review_map.py`, launches game in `-game` mode.
 
 2.  `AGigLineShotActor` iterates the camera list, sets view, calls `HighResShot 1280x720`, waits for capture.
 
@@ -48,6 +48,6 @@
 
 1.  Blender headless (`Tools/export_*.py`) reads `.blend` files, applies metre→centimetre conversion, exports FBX with `ue_metric_v1` preset.
 
-2.  Unreal headless (`Tools/ue_import_*.py`) imports FBX via Interchange, places meshes at geographic coordinates, sets collision profiles.
+2.  Unreal headless (`Tools/unreal/ue_import_*.py`) imports FBX via Interchange, places meshes at geographic coordinates, sets collision profiles.
 
-3.  `Tools/ue_build_demo_map.py` assembles `DemoMap`: creates/repositions actors, sets lighting, saves map and assets.
+3.  `Tools/unreal/ue_build_demo_map.py` assembles `DemoMap`: creates/repositions actors, sets lighting, saves map and assets.

Docs/Architecture/10_quality_requirements.md

@@ -22,7 +22,7 @@ Ordered by priority: realism first, performance last. The order decides design t
 
 | ID | Source/Stimulus | Response | Metric |
 | --- | --- | --- | --- |
-| QS-1 | Screenshot is compared against its reference photograph | The render reads as the same building | Similarity score and visual match confirmed by the owner; `Tools/visual_loop.py` reports the deltas |
+| QS-1 | Screenshot is compared against its reference photograph | The render reads as the same building | Similarity score and visual match confirmed by the owner; `Tools/review/visual_loop.py` reports the deltas |
 | QS-2 | A façade is placed from measured data | It sits on its verified footprint | World span probed against `Geo/verification/` within ~1 m |
 | QS-3 | Player walks both sides of the demo | No fall-through, character stays at ground Z | 0 raycast holes in 84-sample transect |
 | QS-4 | Player holds W for 2 s on flat road | Character moves forward | ≥ 200 cm displacement, Z constant within ±5 cm |
@@ -41,5 +41,5 @@ Ordered by priority: realism first, performance last. The order decides design t
 | BR-1 | A building with a reference photograph has a review shot compared against it | Silhouette and proportion deltas recorded per building in `Screenshots/README.md`; owner approval per shot |
 | BR-2 | Every building is either photo-matched or explicitly recorded as an unfounded blockout | List in `TODO.md`; no building in an in-between state |
 | BR-3 | Every building has a collision proxy and at least one LOD | Count of buildings missing either = 0 |
-| BR-4 | No surface carries a placeholder material | Material audit in `Tools/ue_audit_scene.py` reports 0 placeholder slots |
+| BR-4 | No surface carries a placeholder material | Material audit in `Tools/unreal/ue_audit_scene.py` reports 0 placeholder slots |
 | BR-5 | The realism pass does not break the floor | QS-9 still holds at 1440p, with the measured cost of the pass recorded |