Bump to v0.2.1 (maintenance): CI now verifies the NSIS installer contents via 7z

- Add a 'Verify Windows installer contents' step (7z l shows Step Line.exe +
  uninstall.exe) so the TODO verification items are proven by CI output
- Rebuild 0.2.1 binaries (embedded PCK) and AppImage locally; smoke clean;
  57/57 tests

TODO.md

@@ -5,10 +5,11 @@
 - [x] Extend `tools/generate_textures.py` with an OpenRouter image-API mode
       (`--ai`, `--prompt`, `--name`, `--model`, `--size`), decoding base64 PNG
       responses and clamping output to ≤1024px.
-- [x] Verify a live `--ai` generation against a real `OPENROUTER_API_KEY`
-      (generated `ai/brick_facade.png`, `ai/concrete.png`, `ai/asphalt.png` at
-      1024×1024; fixed the seedream min-pixel requirement by requesting 2048px
-      and downscaling).
+- [x] Add prompts for all 15 game textures (world surfaces, awning, skyline,
+      vignette, 4 HUD icons, 5 access cards) and generate them under `assets/textures/ai/`.
+- [ ] Make the `ai/` icons/vignette/skyline truly transparent: seedream-4.5 ignores
+      `background: transparent` (returns opaque images). Either switch to a
+      transparency-capable model or post-process (e.g. chroma-key the flat background).
 
 ## 🪟 Windows installer (self-contained, all game data)