- Add genre, label, copyright fields to ExtTrackMetadata and DownloadResponse
- Add utils.randomUserAgent() for extensions to get random User-Agent strings
- Fix VM race condition panic by adding mutex locks to all provider methods
- Fix Tidal release date fallback when req.ReleaseDate is empty
- Display genre, label, copyright in track metadata screen
- Store extended metadata in download history for persistence
- Add trackGenre, trackLabel, trackCopyright localization strings