Add NPC backwards-walking bug to TODO

TODO.md

@@ -8,6 +8,10 @@ pass. Anonymous downloads are enabled on the host.
 The scheduled presentation pass is complete (see `DONE.md`). The next scheduled pass is the
 graphics-quality work in [`docs/plan-graphics-v0.6.md`](docs/plan-graphics-v0.6.md).
 
+## Bug Fix NPCs walking backwards
+
+- [ ] Investigate and fix the issue causing NPCs to walk backwards during movement.
+
 ## Graphics quality — Blender-authored NPC characters (v0.6.0)
 
 Detailed plan: [`docs/plan-graphics-v0.6.md`](docs/plan-graphics-v0.6.md) · [ADR-0013](docs/adr/0013-blender-authored-npc-characters.md)