feat: initialize FiltersHandler in main server configuration

Add FiltersHandler to server initialization to enable saved filters API endpoints.

Changes to cmd/server/main.go:
- Initialize filtersHandler using handlers.NewFiltersHandler(queries)
- Add FiltersHandler to Config struct for route registration

This enables the following API endpoints:
- GET /api/saved-filters?resource_type=X - List filters
- POST /api/saved-filters - Create filter
- PUT /api/saved-filters/:id - Update filter
- DELETE /api/saved-filters/:id - Delete filter

Part of saved filters feature implementation.

cmd/server/main.go

@@ -122,6 +122,7 @@ func main() {
 	collectionHandler := handlers.NewCollectionHandler(queries, libraryService, connManager)
 	dashboardService := services.NewDashboardService(queries)
 	dashboardHandler := handlers.NewDashboardHandler(queries)
+	filtersHandler := handlers.NewFiltersHandler(queries)
 	mediaHandler := handlers.NewMediaHandler(queries, libraryService, worker)
 	matchingHandler := handlers.NewMatchingHandler(queries, connManager)
 	jobsHandler := handlers.NewJobsHandler(queries, worker)
@@ -178,6 +179,7 @@ func main() {
 		AnalyticsHandler:      analyticsHandler,
 		QueueHandler:          queueHandler,
 		CollectionHandler:     collectionHandler,
+		FiltersHandler:        filtersHandler,
 		DashboardHandler:      dashboardHandler,
 		DashboardService:      dashboardService,
 		OPDSHandler:           opdsHandler,