feat: sync series from data files after setup/directory update

- Call sync_series_from_data_files after initial setup completes
- Call sync_series_from_data_files when anime directory is updated
- Return synced_series count in directory update response

src/server/api/auth.py

@@ -66,6 +66,29 @@ async def setup_auth(req: SetupRequest):
         # Save the config with the password hash and anime directory
         config_service.save_config(config, create_backup=False)
         
+        # Sync series from data files to database if anime directory is set
+        if anime_directory:
+            try:
+                from src.server.services.anime_service import (
+                    sync_series_from_data_files,
+                )
+                import structlog
+                logger = structlog.get_logger(__name__)
+                sync_count = await sync_series_from_data_files(
+                    anime_directory, logger
+                )
+                logger.info(
+                    "Setup complete: synced series from data files",
+                    count=sync_count
+                )
+            except Exception as e:
+                # Log but don't fail setup if sync fails
+                import structlog
+                structlog.get_logger(__name__).warning(
+                    "Failed to sync series after setup",
+                    error=str(e)
+                )
+        
         return {"status": "ok"}
         
     except ValueError as e: