Gate library prop collision coverage across venues

TODO.md

@@ -122,8 +122,14 @@ except the rebuilt assets themselves.
       and the 40–400 px/m authored band plus the 250 px/m fabric floor; the pose→bone contract is
       covered by `test_pose_reaches_the_skeleton_bones`; LOD/impostor already has
       `test_avatar_mesh_budget_and_lod_swap`. Collider coverage is still open — split below.)
-- [ ] Add a collider/proxy coverage check: every library prop that blocks walking has a
+- [x] Add a collider/proxy check: every library prop that blocks walking has a
       `StaticBody3D` + `NavigationObstacle3D`, checked against the catalogue.
+      (`world_builder.gd` tags every library node with a `library_prop` meta and declares the
+      non-blocking `marquee`/`handrail`/`lantern`/`door` set; two tests in `test_world.gd`
+      verify placed props (body + shape + avoidance radius, all three venues) and library
+      dressing (body unless documented exempt). Mutation-checked: removing `_add_prop_collision`
+      fails 3 tests, dropping `handrail` from the exemption list fails with the exact node.
+      Suite is 275/275.)
 - [x] Add a coverage test so every catalogue asset has a scorecard row and verdict.
       (`tools/test_model_review.py`: every `CHARACTERS`/`GEAR`/`PROPS` entry needs a row in
       `docs/3d-model-review.md`, and character rows need a non-empty verdict.)