feat(review): Blender screenshots beside the in-game captures, with signoff

Two tools for the comparison the review was missing.

- Tools/blender_screenshots.py renders out of a .blend: one image per mesh object, and
  four turntable angles of the whole scene, framed from the scene's own bounds so adding
  geometry never silently crops a shot. Output lands in Screenshots/blender/, beside the
  in-game captures.
- Tools/build_comparison_md.py writes Screenshots/COMPARISON.md: a table with the in-game
  capture and its Blender render side by side per row, then a signoff table with one row
  per in-game screen. Unmatched shots show an em dash rather than disappearing, because a
  missing Blender render is information too.

The first run already earns its keep: the Blender render of the owner's hot hatch is red
with clear glazing, while the in-game capture of the same asset is near-black, so the
material colour is being lost on import - visible in one glance in the new page.

Screenshots/COMPARISON.md

@@ -0,0 +1,42 @@
+# Blender vs in-game
+
+Generated by `Tools/build_comparison_md.py` — do not edit by hand.
+
+- In-game captures: `Screenshots/demo/` (9 files)
+- Blender renders: `Screenshots/blender/` (22 files), made by `Tools/blender_screenshots.py`
+
+Left is what the engine draws, right is what Blender has. A gap between them is the import problem, not a taste problem: scale, material colour, missing parts and split systems all show up here before they show up in a review.
+
+## Side by side
+
+| In-game | Blender | Shot |
+| --- | --- | --- |
+| <img src="demo/review-demo-crossing.png" width="520"> | — | `review-demo-crossing.png` |
+| <img src="demo/review-demo-north-buildings.png" width="520"> | — | `review-demo-north-buildings.png` |
+| <img src="demo/review-demo-retail-frontage.png" width="520"> | — | `review-demo-retail-frontage.png` |
+| <img src="demo/review-demo-spawn-view.png" width="520"> | — | `review-demo-spawn-view.png` |
+| <img src="demo/review-demo-street-level.png" width="520"> | — | `review-demo-street-level.png` |
+| <img src="demo/review-demo-third-person-front.png" width="520"> | <img src="blender/character-angle-035.png" width="520"> | `review-demo-third-person-front.png` |
+| <img src="demo/review-demo-third-person-walk.png" width="520"> | <img src="blender/character-angle-035.png" width="520"> | `review-demo-third-person-walk.png` |
+| <img src="demo/review-demo-third-person.png" width="520"> | <img src="blender/character-angle-035.png" width="520"> | `review-demo-third-person.png` |
+| <img src="demo/review-demo-vehicle.png" width="520"> | <img src="blender/vehicle-angle-035.png" width="520"> | `review-demo-vehicle.png` |
+
+4 of 9 in-game captures have a Blender counterpart; the rest are street and building shots whose meshes come from the Geo pipeline rather than a .blend.
+
+## Signoff
+
+One row per in-game screen. `—` in Blender means there is nothing to compare against.
+
+| # | In-game screen | Blender counterpart | Verdict | Notes |
+| --- | --- | --- | --- | --- |
+| 1 | `review-demo-crossing.png` | — | ☐ |  |
+| 2 | `review-demo-north-buildings.png` | — | ☐ |  |
+| 3 | `review-demo-retail-frontage.png` | — | ☐ |  |
+| 4 | `review-demo-spawn-view.png` | — | ☐ |  |
+| 5 | `review-demo-street-level.png` | — | ☐ |  |
+| 6 | `review-demo-third-person-front.png` | `character-angle-035.png` | ☐ |  |
+| 7 | `review-demo-third-person-walk.png` | `character-angle-035.png` | ☐ |  |
+| 8 | `review-demo-third-person.png` | `character-angle-035.png` | ☐ |  |
+| 9 | `review-demo-vehicle.png` | `vehicle-angle-035.png` | ☐ |  |
+
+Verdicts: ☐ pending · ☑ approved · ☒ rejected. The authoritative per-shot review stays in [README.md](README.md); this page exists to compare Blender against the engine.