Add the MakeHuman-head character head source (head=mh) with project eyes/brows/mouth and CC0 attribution

CREDITS.md

@@ -40,6 +40,15 @@ kept outside version control.
 The CC-BY preview images are included only as development evidence. Any future
 shipped derivative of CesiumMan or RiggedFigure must keep the attribution above.
 
+### MakeHuman head source
+
+The decimated head used by the character 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 retargeted, decimated and re-weighted by
+project scripts; the exported character GLBs remain project assets. See ADR-0015
+and `docs/npc-model-sourcing.md`.
+
 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
 Sunset Strip block; the game does not claim endorsement by, or an exact replica