Fix NPCs walking backwards

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.

DONE.md

@@ -814,3 +814,19 @@ lookup, constants, gamepad bindings, and settings persistence.
       deadzone, remap descriptor/apply/labels, and settings persistence for camera and bindings.
 - [x] Added `smoke_movement.gd` (windowed) and `11-precision-walk.png` with a movement catalogue
       entry, AI mockup, and compare coverage.
+
+## NPC Facing During Movement
+
+Completed 2026-11-01 (post-v0.5.0, pre-v0.6.0). Headless suite **209/209**.
+
+- [x] Root cause: `NpcAvatar` used Godot's `look_at()`, which aims the node's **-Z** axis at
+      the target, but the procedural rig's face (eyes, brows, mouth, focus disc) and every
+      Blender-authored successor face **+Z**. Every walking NPC therefore showed its face
+      toward the side it was leaving.
+- [x] Added the pure `NpcAvatar.yaw_towards(direction)` helper (+Z forward, tested at +Z/+X/-Z
+      and an arbitrary direction), and replaced `look_at()` in the navigation and direct-move
+      paths plus the reaction-face turn.
+- [x] Corrected the head-turn offsets to use the same +Z convention (`basis.z` instead of
+      `-basis.z`), so noticed NPCs still look at the guard with the fixed facing.
+- [x] Added `test_yaw_faces_the_movement_direction`; recaptured the targeting screenshot to
+      confirm NPCs now show their back only when walking away.