Eliminate redundant work and minor issues found during code review:
- Replace manual PlaylistTrack construction in syncPlaylist with the
existing Playlist.AddMediaFiles helper, removing duplicated logic
- Pre-sanitize track fields once per artist batch in the matcher's
fuzzy matching loop, avoiding redundant sanitization in both
findBestMatch and computeSpecificityLevel on every iteration
- Cache resolved usernames in discoverAndSync to avoid N+1 DB lookups
when multiple playlists share the same owner
- Use the local loadedPlugin variable instead of reading m.plugins[p.ID]
after releasing the lock in loadPluginWithConfig
- Fix misleading uint32 comparison (<=0 to ==0) in durationProximity
- Update stale comment on checkTracksEditable to mention plugin playlists