feat: URL state for shareable filter views

- Dashboard filters (year, district, museum, quarter) sync to URL
- Comparison filters (preset, dates, district, museum) sync to URL
- Users can now share links with specific filter configurations
- Reset filters also clears URL parameters
- Add useUrlState hook (unused but available for future use)

src/hooks/index.js

@@ -0,0 +1 @@
+export { useUrlState } from './useUrlState';