Moves perform_nfo_repair_scan and its helpers (_repair_one_series,
_NFO_REPAIR_SEMAPHORE) into folder_scan_service.py so NFO repair runs
during the scheduled folder scan instead of on startup.
- Removes NFO repair code from initialization_service.py
- Updates all test imports and patch targets
- Updates docs/NFO_GUIDE.md and docs/CHANGELOG.md references
All 174 related tests pass.