feat(scheduler): add folder_scan_enabled toggle to SchedulerConfig

- Add folder_scan_enabled boolean field (default false) to SchedulerConfig
- Update data/config.json example with new field
- Add checkbox to setup.html and include in JS payload
- Handle field in auth.py setup endpoint
- Expose field in scheduler API response
- Log and return field in scheduler_service.py
- Update docs/CONFIGURATION.md and docs/ARCHITECTURE.md
- Update index.html UI, app.js and scheduler-config.js handlers
- Verified backward compatibility: old configs load with default False

src/server/services/scheduler_service.py

@@ -145,6 +145,7 @@ class SchedulerService:
             schedule_time=config.schedule_time,
             schedule_days=config.schedule_days,
             auto_download=config.auto_download_after_rescan,
+            folder_scan=config.folder_scan_enabled,
         )
 
         if not self._scheduler or not self._scheduler.running:
@@ -204,6 +205,9 @@ class SchedulerService:
             "auto_download_after_rescan": (
                 self._config.auto_download_after_rescan if self._config else False
             ),
+            "folder_scan_enabled": (
+                self._config.folder_scan_enabled if self._config else False
+            ),
             "last_run": self._last_scan_time.isoformat() if self._last_scan_time else None,
             "next_run": next_run,
             "scan_in_progress": self._scan_in_progress,