Implement Phase 8 of GET_SAVED_FILTER_BY_ID_IMPLEMENTATION.md:
Frontend integration for loading saved filters via GET /:id endpoint.
Completes the saved filters feature with full CRUD functionality.
Changes to web/src/bookshelf.ts:
- Convert loadFilter() from synchronous to async function
- Fetch filter details from GET /api/saved-filters/:id endpoint
- Parse filters JSON (handles both string and object formats)
- Populate hidden #filter-form fields with filter values
- Update visible form fields for user feedback
- Trigger HTMX change event to apply filter
- Show loading, success, and error toasts
- Close filters dropdown after applying filter
- Proper error handling (404, network errors, auth errors)
User Flow:
1. User clicks saved filter in dropdown (server-rendered list)
2. Alpine.js calls GET /api/saved-filters/:id API
3. Receives filter object with filters JSONB
4. Populates form fields (hidden + visible)
5. Triggers HTMX to submit form
6. Books grid updates instantly (no page reload)
SSR-First Compliance:
- ✅ Initial page load: Server renders everything (no API calls)
- ✅ User interaction only: API called when user clicks filter
- ✅ Hybrid approach: Alpine fetches data, HTMX applies it
- ✅ No async x-init data fetching
- ✅ Progressive enhancement maintained
- ✅ Matches dashboard pattern for interactions
Error Handling:
- 404: Filter not found (deleted by another session)
- 401: Not authenticated
- Network errors: Show error toast
- Form not found: Show error toast
Benefits:
- Complete saved filters CRUD functionality
- Instant filter application (no page reload)
- User feedback with toast notifications
- Follows HTMX + Alpine hybrid pattern
- Type-safe TypeScript with proper error handling
Implements Phase 8 from GET_SAVED_FILTER_BY_ID_IMPLEMENTATION.md.