Audit prop budgets and add a prop-gallery art check

- audit_glb decodes geometry: 400 tris / 600 verts budget, degenerate
  triangles, UV range, ground contact, one material; newspaper box parts moved
  to sit on y=0
- capture_prop_gallery.gd renders the six props on a studio backdrop; new
  prop_gallery catalogue entry + AI mockup (compare 10 good, judge match 0.90)
- headless test that instances share the imported atlas material
- README documents the gallery capture and budget; TODO props pipeline section
  moved to DONE

DONE.md

@@ -734,3 +734,21 @@ Completed 2026-11-01 (v0.4.0). Headless **187/187**, Python tooling **53/53**, t
       remove collision; a unit test covers the fallback body, shape, width, and navigation obstacle.
 - [x] Tests: placement validation and its failure modes, variant determinism/range, colliders on
       every placed prop (including obstacle presence), and the fallback collider path.
+
+## Prop Pipeline Checks
+
+Completed 2026-11-01. Python tooling **56/56**, headless **188/188**, prop gallery **match**
+(0.90) in the vision judge, `compare` **10 good / 0 bad**.
+
+- [x] `audit_glb()` now decodes positions/UVs/indices and enforces the art budget
+      (`MAX_TRIANGLES = 400`, `MAX_VERTICES = 600`), rejects degenerate triangles, UVs outside
+      `[0, 1]`, a prop that floats above or sinks below the ground (`min y ~= 0`), and the
+      single-material/atlas contract. The newspaper box sat 3 cm high; its catalogue parts moved
+      down so it rests on y = 0.
+- [x] Added `capture_prop_gallery.gd`: renders all six props on a studio backdrop (two rows on a
+      display platform) to `docs/screenshots/10-prop-gallery.png`, with a `prop_gallery`
+      catalogue entry and AI mockup, so `compare`/`judge` cover close-range prop art.
+- [x] Confirmed instances share the imported atlas material (headless test) and documented the
+      triangle/vertex budget in the pipeline docstring.
+- [x] README lists the gallery capture command and image; the pipeline docstring and audit docs
+      describe the budget checks.