Resolve a song/recording from MusicBrainz (the open, CC0 music encyclopedia). Pass artist + title, or a free-text query (Lucene supported). Returns ranked recordings with MusicBrainz ID (MBID), title, primary artist, length (ms), first-release date, and disambiguation. Keyless, public-domain core data. Use to canonicalize a track to its MBID or cross-reference identity.