Add sync_single_series_after_scan with NFO metadata and WebSocket updates

- Implement sync_single_series_after_scan to persist scanned series to database
- Enhanced _broadcast_series_updated to include full NFO metadata (nfo_created_at, nfo_updated_at, tmdb_id, tvdb_id)
- Add immediate episode scanning in add_series endpoint when background loader isn't running
- Implement updateSingleSeries in frontend to handle series_updated WebSocket events
- Add SERIES_UPDATED event constant to WebSocket event definitions
- Update background loader to use sync_single_series_after_scan method
- Simplified background loader initialization in FastAPI app
- Add comprehensive tests for series update WebSocket payload and episode counting logic
- Import reorganization: move get_background_loader_service to dependencies module

src/server/web/static/js/index/socket-handler.js

@@ -133,6 +133,22 @@ AniWorld.IndexSocketHandler = (function() {
             AniWorld.ScanManager.updateProcessStatus('download', false, true);
         });
 
+        // Series events
+        socket.on(WS_EVENTS.SERIES_UPDATED, function(data) {
+            console.log('Series updated:', data);
+            
+            // Use the data directly to update the series instead of full refresh
+            if (data && data.data && AniWorld.SeriesManager && AniWorld.SeriesManager.updateSingleSeries) {
+                AniWorld.SeriesManager.updateSingleSeries(data.data);
+            } else {
+                // Fallback to full reload if data is incomplete
+                console.warn('Incomplete series update data, falling back to full reload');
+                if (AniWorld.SeriesManager && AniWorld.SeriesManager.loadSeries) {
+                    AniWorld.SeriesManager.loadSeries();
+                }
+            }
+        });
+
         // Series loading events
         socket.on(WS_EVENTS.SERIES_LOADING_UPDATE, function(data) {
             console.log('Series loading update:', data);