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/scheduler_service.py

@@ -356,6 +356,28 @@ class SchedulerService:
             else:
                 logger.debug("Auto-download after rescan is disabled — skipping")
 
+            # Folder scan (daily maintenance)
+            if self._config and self._config.folder_scan_enabled:
+                logger.info("Folder scan is enabled — starting")
+                try:
+                    from src.server.services.folder_scan_service import (  # noqa: PLC0415
+                        FolderScanService,
+                    )
+
+                    folder_scan_service = FolderScanService()
+                    await folder_scan_service.run_folder_scan()
+                except Exception as fs_exc:  # pylint: disable=broad-exception-caught
+                    logger.error(
+                        "Folder scan failed",
+                        error=str(fs_exc),
+                        exc_info=True,
+                    )
+                    await self._broadcast(
+                        "folder_scan_error", {"error": str(fs_exc)}
+                    )
+            else:
+                logger.debug("Folder scan is disabled — skipping")
+
         except Exception as exc:  # pylint: disable=broad-exception-caught
             logger.error("Scheduled rescan failed", error=str(exc), exc_info=True)
             await self._broadcast(