Add catalog search on timeline header and fix Back to Timeline navigation.

Public GET /api/search over artists, movements, and paintings with a debounced header bar on the timeline; Back to Timeline resets zoom and gallery session.

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

Documentation/Plans.md

@@ -5,4 +5,6 @@ this file contains draft for future releases and features
 3. tool to monitor/manage (plan actions) of curator actions, markers to check painting/text ?
 4. tool to sync prod /env resources (both ways), db structure, db data, images, users etc
 5. curator_audit_log should contain log of actions like fixit, checked, upload etc with details for which entity it was made and details what was the action and outcome
+6. ~~create search by entity (painting, artist, movement)~~ — done: timeline header + `GET /api/search`
+7. create guided tours (with text/extra infor, set of entities)