Document the frozen npc_base fallback boundary

TODO.md

@@ -45,8 +45,10 @@ the rest of §C remains the broad review checklist.
       open and gripping at 0.8 m; silhouette, eye/mouth readability, ear/nose/jaw planes, finger
       separation and gear contact. Keep the 16,000/16,000 cap; optional extra bones are allowed, but the required 13 core bones and rest positions must not move.
       Recorded in `docs/3d-model-review.md` §Overhaul acceptance criteria.
-- [ ] Confirm the identity boundary: `npc_base.blend` is the frozen fallback and must not absorb
+- [x] Confirm the identity boundary: `npc_base.blend` is the frozen fallback and must not absorb
       prototype detail unless a separate contract decision approves it.
+      Recorded in `docs/3d-model-review.md` §Baseline inventory and
+      `docs/blender-assets.md` §Frozen fallback boundary.
 - [ ] Choose a local working-set layout: `tmp/npc-parts/<variant>/` (gitignored) for part `.blend`
       and preview GLBs; only the assembled character GLBs, AO/maps, manifest and review sheets are
       committed. Do not add a new committed `.blend` source tree without a docs/ADR decision.