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

docs/CONFIGURATION.md

@@ -117,7 +117,8 @@ Location: `data/config.json`
         "interval_minutes": 60,
         "schedule_time": "03:00",
         "schedule_days": ["mon", "tue", "wed", "thu", "fri", "sat", "sun"],
-        "auto_download_after_rescan": false
+        "auto_download_after_rescan": false,
+        "folder_scan_enabled": false
     },
     "logging": {
         "level": "INFO",
@@ -173,6 +174,7 @@ Controls automatic cron-based library rescanning (powered by APScheduler).
 | `scheduler.schedule_time`              | string       | `"03:00"`                                     | Daily run time in 24-h `HH:MM` format.                               |
 | `scheduler.schedule_days`              | list[string] | `["mon","tue","wed","thu","fri","sat","sun"]` | Days of the week to run the scan. Empty list disables the cron job.  |
 | `scheduler.auto_download_after_rescan` | bool         | `false`                                       | Automatically queue missing episodes for download after each rescan. |
+| `scheduler.folder_scan_enabled`        | bool         | `false`                                       | Run folder maintenance (NFO repair, folder renaming, poster checks) during scheduled runs. |
 
 Valid day abbreviations: `mon`, `tue`, `wed`, `thu`, `fri`, `sat`, `sun`.