Harden installer icon + NSIS rebuild path

- Regenerate icon.ico with classic BMP entries (16/32/48) — PNG-compressed
  ICO entries can fail NSIS' icon loader on some builds
- CI copies assets/textures/icon.ico onto the packaging path right before
  makensis, removing any stale/missing-copy failures
- Recreate v0.2.1 tag after this fix

TODO.md

@@ -68,3 +68,7 @@ performance hardening only.
 - [ ] Profile the crowd: ensure textured materials and props hold target frame rate around a
       busy entrance.
 - [ ] Add LOD or culling for distant NPCs/props if the crowd grows.
+
+## Screenshot Refresh
+
+- [ ] Regenerate and verify the six README screenshots from the current build.