Add data file to database sync functionality

- Add get_all_series_from_data_files() to SeriesApp
- Sync series from data files to DB on startup
- Add unit tests for new SeriesApp method
- Add integration tests for sync functionality
- Update documentation

docs/infrastructure.md

@@ -254,6 +254,25 @@ Deprecation warnings are raised when using these methods.
 
 Main engine for anime series management with async support, progress callbacks, and cancellation.
 
+**Key Methods:**
+
+-   `search(words)` - Search for anime series
+-   `download(serie_folder, season, episode, key, language)` - Download an episode
+-   `rescan()` - Rescan directory for missing episodes
+-   `get_all_series_from_data_files()` - Load all series from data files in the anime directory (used for database sync on startup)
+
+### Data File to Database Sync
+
+On application startup, the system automatically syncs series from data files to the database:
+
+1. After `download_service.initialize()` succeeds
+2. `SeriesApp.get_all_series_from_data_files()` loads all series from `data` files
+3. Each series is added to the database via `SerieList.add_to_db()`
+4. Existing series are skipped (no duplicates)
+5. Sync continues silently even if individual series fail
+
+This ensures that series metadata stored in filesystem data files is available in the database for the web application.
+
 ### Callback System (`src/core/interfaces/callbacks.py`)
 
 -   `ProgressCallback`, `ErrorCallback`, `CompletionCallback`