Narrow the pose-capture discrepancy to the harness and lock bone posing

TODO.md

@@ -64,10 +64,12 @@ except the rebuilt assets themselves.
       frames still show the rest pose; direct bone writes deform the mesh, so this is a staging/
       capture discrepancy that may also affect live venue frames. See
       `docs/3d-model-review.md` §"Pose evidence is blocked".
-- [ ] Diagnose the pose-capture discrepancy: compare the harness staging with the working
-      standalone probe (SceneTree lifetime, node parents, first-frame skin bind, capture timing)
-      and add a scene test asserting a posed avatar renders differently from its rest frame.
-      Do not trust pose sheets or claim rig deformation until that test passes.
+- [ ] Finish the pose-capture diagnosis. Done so far: the pose reaches proxies and skeleton
+      bones (new headless test, 273/273), direct bone rotations deform the rendered mesh, and
+      three standalone probes render the seated crouch — only `capture_npc_pose.gd` saves the
+      rest pose. Remaining leads: reproduce the stage inside `capture_npc_review.gd` (known to
+      render) or capture via `SubViewport` + `RenderingServer.force_draw()`, then add a scene
+      test that a posed avatar renders differently from its rest frame.
 - [ ] UV/texel density: measure the 256² slot maps; decide whether atlas, UDIM or a resolution
       change is justified. Do not change `CHAR_MAX_TRIS`/`CHAR_MAX_VERTS` without re-running the
       budget smoke and the Web/Compatibility path.