refactor: remove legacy data file sync functionality

Series now loaded directly from database. Removed:
- sync_legacy_series_to_db() from anime_service.py
- Corresponding sync call after directory update in config.py
- Safety nets in initialization_service.py for missing progress IDs

src/server/api/config.py

@@ -279,30 +279,15 @@ async def update_directory(
 
         config_service.save_config(app_config)
         
-        # Sync series from data files to database
-        sync_count = 0
-        try:
-            import structlog
-
-            from src.server.services.anime_service import sync_legacy_series_to_db
-            logger = structlog.get_logger(__name__)
-            sync_count = await sync_legacy_series_to_db(directory, logger)
-            logger.info(
-                "Directory updated: synced series from data files",
-                directory=directory,
-                count=sync_count
-            )
-        except Exception as e:
-            # Log but don't fail the directory update if sync fails
-            import structlog
-            structlog.get_logger(__name__).warning(
-                "Failed to sync series after directory update",
-                error=str(e)
-            )
+        # Series are now loaded directly from database, no sync needed
+        logger.info(
+            "Directory updated successfully",
+            directory=directory
+        )
         
         response: Dict[str, Any] = {
             "message": "Anime directory updated successfully",
-            "synced_series": sync_count
+            "synced_series": 0
         }
         
         return response