Document the asset storage convention

Add the path table from ADR-0014 to the architecture documentation (runtime UI/scene
art, tiled textures, models, reference art, QA captures, raw sources) and close the
second storage-restructure TODO item.

TODO.md

@@ -26,7 +26,7 @@ and scene visuals with those mockups — verified with
 - [x] Decide the canonical runtime image root (`assets/images/` for UI/scene art): recorded in
       `MEMORY.md` and [ADR-0014](docs/adr/0014-runtime-image-root.md).
 - [x] Move the reference mockups from `docs/screens/designs/` into the runtime root (keep `docs/screens/designs/` as a docs-only copy or replace it with the new path).
-- [ ] Document one convention for game vs reference vs development images across `assets/textures/`, `assets/images/`, `assets/models/generated/`, `docs/screenshots/`, and `docs/screens/designs/`.
+- [x] Document one convention for game vs reference vs development images across `assets/textures/`, `assets/images/`, `assets/models/generated/`, `docs/screenshots/`, and `docs/screens/designs/` (in `docs/architecture.md`, ADR-0014).
 - [ ] Re-run `godot --headless --path . --import` to regenerate `.import` sidecars after any move.
 - [ ] Confirm `.gitignore` still excludes development-only outputs (concepts, Blender sources, raw AI fabrics) under the new layout.