- downloaded_purchases table in library DB (permanent, per-user)
- V2 commands: mark_downloaded, remove_downloaded, get_downloaded_track_ids
- Frontend enriches purchase data with download status from backend
- Grid overlay for unavailable albums centered on artwork
- Quality filter expanded: All / Hi-Res / CD / Lossy (radio group)
- Album download status derived from track-level registry
Create qbz-library crate with:
- LibraryScanner: directory scanning for audio files
- MetadataExtractor: audio metadata extraction via lofty
- LibraryDatabase: SQLite persistence with WAL mode
- CueParser: CUE sheet parsing for single-file albums
- Thumbnails: artwork extraction and thumbnail generation
- Tag sidecar: album metadata override files
src-tauri re-exports from qbz-library for backwards compatibility.
Enables TUI/headless clients to manage local libraries without Tauri.