The HIGH-quality lossy format picker can now produce an AAC/M4A 320 kbps output alongside MP3 and Opus. FFmpegService.convertM4aToLossy/convertAudioFormat, the Dart queue pipeline, the Kotlin finalizer, and the library database format helper all route .m4a through a unified aac codec path and tag the resulting file with the M4A metadata writer. The Lossy Format setting gains a new option, and the track metadata convert dialog lists AAC next to the other targets.
Apple Music lyrics gain a 'eLRC word sync' switch (default off). When disabled the pax-to-LRC formatter strips inline word timestamps, producing line-synced LRC that is safer for players that choke on eLRC; enabling it restores the previous word-by-word behaviour. The change propagates through SetLyricsFetchOptions and invalidates the global lyrics cache on toggle.
Broad l10n migration: roughly 400 previously hardcoded English strings across queue, settings, track metadata, repo, audio analysis, setup and extension screens now live in the ARB catalog, with matching plural/placeholder forms. No behaviour change beyond localisation. Existing and new unit tests (lyrics eLRC toggle and Dart settings round-trip) pass.
- Extract normalizeOptionalString() to lib/utils/string_utils.dart from download_queue_provider and track_metadata_screen
- Extract PrioritySettingsScaffold widget from lyrics and metadata priority pages, reducing ~280 lines of duplication
- Extract _ensureDefaultDocumentsOutputDir/_ensureDefaultAndroidMusicOutputDir in download queue provider
- Extract collectLibraryAudioFiles() and applyDefaultLibraryMetadata() in Go library_scan.go
- Extract plainTextLyricsLines() in Go lyrics.go, used by Apple Music, Musixmatch, and QQ Music clients