feat: remove startup NFO repair, update docs and tests

- Remove NFO repair scan step from ARCHITECTURE.md startup sequence
- Update CHANGELOG.md: rephrase perform_nfo_repair_scan as scheduled scan
- Add test verifying perform_nfo_repair_scan is NOT called in lifespan
- Keep existing folder scan wiring tests and unit tests intact
- NFO_GUIDE.md already correctly describes scheduled scan behavior

docs/CONFIGURATION.md

@@ -174,7 +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. |
+| `scheduler.folder_scan_enabled`        | bool         | `false`                                       | Run folder maintenance (NFO repair, folder renaming, poster checks) during scheduled runs. **When enabled, series folders are automatically renamed to match the `<title> (<year>)` convention derived from their `tvshow.nfo` files.** |
 
 Valid day abbreviations: `mon`, `tue`, `wed`, `thu`, `fri`, `sat`, `sun`.
 
@@ -218,6 +218,7 @@ Source: [src/server/models/config.py](../src/server/models/config.py#L15-L24)
 - Obtain a TMDB API key from https://www.themoviedb.org/settings/api
 - `auto_create` creates NFO files during the download process
 - `update_on_scan` refreshes metadata when scanning existing anime
+- `download_poster` also controls whether the scheduled folder scan checks for and re-downloads missing or corrupted `poster.jpg` files (see [NFO_GUIDE.md](NFO_GUIDE.md#6-poster-check))
 - Image downloads require valid `tmdb_api_key`
 - `TMDB_API_KEY` environment variable is optional when `nfo.tmdb_api_key` is configured in `data/config.json`
 - Larger image sizes (`w780`, `original`) consume more storage space