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/release-checks.md

@@ -50,7 +50,7 @@ Measured at 1440p on the development workstation: Bazzite, Ryzen 7 7700X, 64 GB
 
 ## `0.1.0` — Placement vs references — record (2026-11-08)
 
-Checked against the reference photography (`Art/reference/`) and the Geo measurements (`Geo/verification/*`). Build under test: current `main` content, DemoMap rendered via `Tools/render_screenshots.sh` (2026-11-08, Vulkan SM5, 1920×1080); engine positions probed from the DemoMap (commandlet, 2026-11-08).
+Checked against the reference photography (`Art/reference/`) and the Geo measurements (`Geo/verification/*`). Build under test: current `main` content, DemoMap rendered via `Tools/review/render_screenshots.sh` (2026-11-08, Vulkan SM5, 1920×1080); engine positions probed from the DemoMap (commandlet, 2026-11-08).
 
 ### Placement and scale (in-engine ↔ reference)
 
@@ -82,7 +82,7 @@ Checked against the reference photography (`Art/reference/`) and the Geo measure
 - **Crossing ramps are kerb flushes, not graded ramps** — the `0.1.1` Crossing ramp gradient item.
 - Site identity (the neoclassical hero with motto band) matches the 2009 façade photograph and the 1922 Masonic elevation within blockout fidelity.
 
-Pre-check method: `Tools/judge_screenshot.py` (vision model) flagged the simplified flat surfaces as "unexpected" — those flags are the deliberate deviations above, not placement errors. Final verdict is by human review of the shots in `Screenshots/demo/`.
+Pre-check method: `Tools/review/judge_screenshot.py` (vision model) flagged the simplified flat surfaces as "unexpected" — those flags are the deliberate deviations above, not placement errors. Final verdict is by human review of the shots in `Screenshots/demo/`.
 
 ## `0.1.0` — Collision and packaging — audit note (2026-11-08)
 
@@ -90,7 +90,7 @@ Run on the packaged build (`GigLineQA`, Development, Vulkan SM5) with `-qaselfte
 
 - **Transect (holes/gaps):** 1456 samples over 16 rows — lane centres **plus the kerb/road/sidewalk seam Ys** (−1382, −1053, +718, +1047 and neighbours) and X −20000..−2000. Result **0 holes**. (The old 84-sample check covered only 3 lane centres; the seam rows are what this check adds.)
 - **Invisible-wall probe:** horizontal traces 30 m long, grounded at 160 cm above the local ground, along the road and both seam rows. Result **0/35 blocking hits inside 21 m** — no invisible walls or misplaced blockers in the street envelope.
-- **Facade occlusion probe:** from the road centre, 40 m traces sideways at walking height toward each frontage, required only where the map stages a building (the spans are listed in `AGigLineCharacter` and mirror `Tools/ue_build_demo_map.py`). Result **0/9 directions without a blocking wall** — the player cannot walk through the hero or the frontage. This probe found the hero façade had **no simple collision** at all (complex-only, so traces and capsule sweeps passed through it); it is now `UseComplexAsSimple`. Auto-generated convex hulls were tried first and rejected: on a 95-part, 26 m façade they bulged into the street (the wall probe went 0/35 → 2/35). (First pass used a fixed Z 160 start; the street is at Z ~366, so the probe started inside the earth and reported every row as a dist-0 blocker. Grounding the probe fixed that measurement bug.)
+- **Facade occlusion probe:** from the road centre, 40 m traces sideways at walking height toward each frontage, required only where the map stages a building (the spans are listed in `AGigLineCharacter` and mirror `Tools/unreal/ue_build_demo_map.py`). Result **0/9 directions without a blocking wall** — the player cannot walk through the hero or the frontage. This probe found the hero façade had **no simple collision** at all (complex-only, so traces and capsule sweeps passed through it); it is now `UseComplexAsSimple`. Auto-generated convex hulls were tried first and rejected: on a 95-part, 26 m façade they bulged into the street (the wall probe went 0/35 → 2/35). (First pass used a fixed Z 160 start; the street is at Z ~366, so the probe started inside the earth and reported every row as a dist-0 blocker. Grounding the probe fixed that measurement bug.)
 - **Walk / reset / pause:** 761 cm in 2 s (Z steady 456), reset 0 cm, pause `IsGamePaused()=1`, unpause 0 — all PASS.
 - Packaging: the packaged build launches, reaches gameplay, and the QA run quits cleanly. The `GigLineShotActor` screenshot rounds are suppressed under `-qaselftest` so they cannot quit the run before the audit phases.
 - Caveat recorded: ground Z extremes (−12 m / 3000 cm) are trace-start/terrain-edge artifacts of the widened extent, not walkable holes — the walkable corridor is continuous (walk + transect both PASS).