Enhance timeline and movement flow UI; add fetched painting images.

Timeline: era and historical-event click-to-zoom, event markers from historical-events.ts. Movement flow: shared zoom/pan, viewport-fit layout, curved lineage streams, hover-to-reveal artist lifespans on stacked lanes. Docs updated. Includes batch-fetched paintings and regenerated thumbs.
Co-authored-by: Cursor <cursoragent@cursor.com>

Documentation/setup.md

@@ -70,7 +70,7 @@ npm run fetch-images -- --limit=50 --max-wait=120 # same batch size, longer look
 cd client && npm run build && cd ..
 ```
 
-Image fetch can take hours for the full catalog (~900+ missing works after seed). Use **`npm run fetch-images -- --limit=N`** for random batches (10s per painting by default), **`--artist="…"`** for one artist in catalog order, or on-demand resolution when viewing a painting in the detail view.
+Image fetch can take hours if you run it for the entire catalog. The first line of each run reports **`Missing local files: N`**. Use **`npm run fetch-images -- --limit=N`** for random batches (10s per painting by default), **`--artist="…"`** for one artist in catalog order, or on-demand resolution when viewing a painting in the detail view.
 
 ## Run
 
@@ -103,6 +103,7 @@ Open http://localhost:3001 (or your configured `PORT`).
 | `npm run search-missing-paintings` | ↑ (alias) | Same as `fetch-images` |
 | `npm run fetch-images -- --artist="Name"` | ↑ | Limit to one artist (catalog order) |
 | `npm run fetch-images -- --limit=50` | ↑ | Random sample of N missing paintings |
+| `npm run fetch-images -- --limit=250` | ↑ | Larger random batch (processes min(N, missing count)) |
 | `npm run fetch-images -- --limit=50 --max-wait=120` | ↑ | Random batch; 120s cap per painting |
 | `npm run fetch-images -- --discover-only --limit=20` | ↑ | Fix `wikipedia_title` via search only |
 | `npm run regenerate-thumbnails` | `scripts/regenerate-thumbnails.js` | Rebuild all thumbs from full local files |