Migrate entity rendering from ColorRect placeholders to Sprite2D with
rendered PNGs at -72.5° from horizontal. Key changes:
- Sprite2D.centered=false, scale=0.5 for 64px source → 32px runtime
- self_modulate for D-033 relationship tinting (modulate.a reserved
for D-015 peripheral dimming)
- 8-octant to 4-cardinal direction mapping for sprite selection
- Feet-anchored ENTITY_OFFSET_Y for correct y-sort with tilted sprites
- Facing indicator repositioned to sprite local center (32,32)
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>