Avatars called Godot's look_at(), which points the node's -Z axis at the target,
but the rig's face (eyes/brows/mouth/focus disc, and the Blender successor) is on
+Z. Every walking NPC therefore faced away from its movement direction.
- add the pure yaw_towards(direction) helper (+Z forward) and use it in both
movement paths and the reaction face-turn
- fix the head-turn offset to the same +Z convention (basis.z)
- test +Z/+X/-Z/arbitrary directions; recapture targeting screenshot
- TODO bug item moved to DONE, MEMORY records the convention
Headless 209/209.