Detailed graphics pass: authored textures, humanoid NPCs, HUD feedback, asset pipeline

- tools/generate_textures.py (deterministic PIL) produces all authored PNGs:
  brick facade, concrete, asphalt, awning, skyline, vignette, HUD icons,
  access-card art (all <=1024px, power-of-two)
- WorldBuilder: textured facade/glass door/sidewalk/asphalt, striped awning
  with 'STEP LINE', generated skyline backdrop planes
- GameManager: soft sun shadows (4-split parallel); guard in 'guard' group
- NPC avatars: humanoid rig (torso/head/limbs) with archetype props (camera,
  delivery box, performer hat, protest sign, tourist backpack), procedural
  walk bob, head-turns-toward-guard attention cue
- HUD: inspection artifact cards, mode icons (flashlight/door/wand),
  per-escalation vignette, body-camera overlay (corner brackets + REC + clock)
- assets/ import convention documented; test_asset_textures_present_and_pow2
  guards the pipeline (57 tests pass)
- README tech stack updated for Gitea Actions + asset pipeline; screenshot
  gallery regenerated (day + night)

DONE.md

@@ -173,6 +173,21 @@ Completed task sections moved from `TODO.md`. Sections are moved only when every
 - [x] `config/version` → `0.2.0`; `build/` artifacts rebuilt and Linux binary smoke-tested.
 - [x] New world/lighting headless tests (56 total).
 
+## 🎮 Assets & detailed graphics pass (textures, rigs, UI feedback)
+
+- [x] Authored texture set via `tools/generate_textures.py` (deterministic PIL): brick facade,
+      seamless concrete, asphalt, awning, skyline, vignette, HUD icons, access-card art — all
+      ≤1024px and power-of-two; imported under `assets/textures/`.
+- [x] Environment: textured facade + glass door, concrete sidewalk, asphalt street, striped
+      awning with “STEP LINE”, generated skyline backdrop planes, soft sun shadows.
+- [x] NPCs: humanoid rig (torso/head/limbs) with archetype props (camera, delivery box, hat,
+      sign, backpack), procedural walk bob, head-turns-toward-guard cue.
+- [x] UI/feedback: inspection artifact cards, mode icons (flashlight/door/wand), escalation
+      vignette, body-camera overlay (corner brackets + REC + shift clock).
+- [x] Assets convention documented in README; `test_asset_textures_present_and_pow2` guards
+      the pipeline (57 tests total).
+- [ ] (remaining, in TODO) crowd performance profiling and LOD/culling when the crowd grows.
+
 ## CI — cache timeout mitigation
 
 - [x] Remove `actions/cache@v4` from the checks job (runner cannot reach GitHub's cache