feat: integrate NFO repair into scheduled folder scan

- Add FolderScanService.run_folder_scan() calling perform_nfo_repair_scan()
- Remove startup-time NFO repair from fastapi_app lifespan
- Update docs/NFO_GUIDE.md: repair now runs as part of daily scan
- Update tests to verify integration wiring
- Update ARCHITECTURE.md and scheduler_service for scan scheduling

docs/ARCHITECTURE.md

@@ -81,6 +81,7 @@ src/server/
 |   +-- websocket_service.py# WebSocket broadcasting
 |   +-- queue_repository.py # Database persistence
 |   +-- nfo_service.py      # NFO metadata management
+|   +-- folder_scan_service.py # Daily folder maintenance scan
 +-- models/                 # Pydantic models
 |   +-- auth.py             # Auth request/response models
 |   +-- config.py           # Configuration models