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

src/server/services/initialization_service.py

@@ -417,10 +417,10 @@ async def _repair_one_series(series_dir: Path, series_name: str) -> None:
 async def perform_nfo_repair_scan(background_loader=None) -> None:
     """Scan all series folders and repair incomplete tvshow.nfo files.
 
-    Runs on every application startup (not guarded by a run-once DB flag).
-    Checks each subfolder of ``settings.anime_directory`` for a ``tvshow.nfo``
-    and calls ``_repair_one_series`` for every file with absent or empty
-    required tags.
+    Called from ``FolderScanService.run_folder_scan()`` during the scheduled
+    daily folder scan (not on every startup).  Checks each subfolder of
+    ``settings.anime_directory`` for a ``tvshow.nfo`` and calls
+    ``_repair_one_series`` for every file with absent or empty required tags.
 
     Each repair task creates its own isolated :class:`NFOService` /
     :class:`TMDBClient` so concurrent tasks never share an ``aiohttp``