- Add migration_legacy_files_completed flag to SystemSettings model
- Create legacy_file_migration service to migrate series from key/data files
- Integrate legacy migration into initialization_service startup flow
- Add integration tests for legacy file migration
- Update DATABASE.md documentation with migration details
- Fix various test and service issues (nfo_repair, tmdb_client, download_service)
- Add test_database_schema unit tests
- Add ffmpeg to Dockerfile.app for container HLS support
- Configure yt-dlp with --downloader ffmpeg --hls-use-mpegts
- Add startup health check warns if ffmpeg missing
- Update DEVELOPMENT.md with ffmpeg prerequisites and troubleshooting
- Add tests for ffmpeg HLS options and health check
