The download-time ISRC index now also parses mp3, m4a, ogg, and opus
tags through the existing native readers instead of skipping everything
but .flac. Library settings gain a Review duplicates sheet that groups
history and local-library rows sharing an ISRC via SQL over the
attached databases (no filesystem walk, SAF-safe), shows quality
badges, and offers keep-best and per-copy delete with confirmation.