Rewrite NPC plans around the Quaternius base

CREDITS.md

@@ -48,10 +48,20 @@ shipped derivative of CesiumMan or RiggedFigure must keep the attribution above.
 
 The standalone MakeHuman head prototype is derived from the MakeHuman / MPFB base
 mesh, **CC0** (`assets/models/blender_src/makehuman_head.glb`; source
-`tmp/npc-research/makehuman/base.obj` with its bundled
-`LICENSE.md`/`LICENSE.ASSETS.md`). It is cut, retopologised and re-weighted by
-project scripts; the exported character GLBs remain project assets. See ADR-0015
-and `docs/npc-model-sourcing.md`.
+<https://static.makehumancommunity.org/makehuman.html>, MakeHuman base mesh,
+CC0 1.0). It is cut, retopologised and re-weighted by project scripts; the exported
+character GLBs remain project assets. The development source files were removed
+from `tmp/` after the 2026-11-05 pivot to Quaternius. The head is retained as a
+tested fallback, not the active NPC base. See ADR-0017 and
+`docs/npc-model-sourcing.md`.
+
+### Quaternius NPC base source
+
+The active NPC base migration uses **Quaternius Ultimate Modular Characters** and
+**Ultimate Modular Women** (CC0 1.0, <https://quaternius.com/>). The three
+researched GLBs are development inputs and are not shipped directly; the baked,
+retargeted character GLBs are project assets. See ADR-0017 and
+`docs/npc-model-sourcing.md` for the decision, source hashes and rollout status.
 
 The venue geometry is authored procedurally in `src/game/world_builder.gd` as a
 stylized reconstruction. The Joke Shop is a fictional stand-in for the real