Improve 3D gallery and debug checkup workflow for image curation.

Add parquet floor, museum-style exit, movement-tinted walls, and gold/black
frames with gallery sync after Fix it. Debug panel gets Checked and Fix it
buttons; documentation and image-fetch reliability updates included.

Co-authored-by: Cursor <cursoragent@cursor.com>

Documentation/setup.md

@@ -168,4 +168,7 @@ After clone: copy `.env.example` → `.env`, install dependencies, run `npm run
 | Permission denied creating tables | `gallery` user lacks CREATE | Run admin grants, then migrate |
 | Wikipedia API rate limit during fetch | Too many requests in a row | Wait and re-run; scripts retry with backoff |
 | Checkup **Reviewed** toggle returns 404 | Stale server process missing new routes | Restart `npm run dev` after pulling API changes |
+| **Fix it** fails with `read ECONNRESET` | Remote host dropped connection | Restart server; client sends `searchUrl` / `source`; retry or use Commons URL in overrides |
+| Fixed image not shown in 3D gallery | Stale gallery session or cached texture | Rebuild client; fix updates session + `?v=` revision — use **Back to Gallery** (not browser back) |
+| Frame still black after **Checked** | Gallery session not synced | Re-enter hall or toggle debug **Checked** from detail with gallery open behind overlay |
 | Duplicate works in gallery / timeline | Double import or variant Wikipedia titles | `npm run find-duplicates`; merge or delete spare rows manually |