Add ReadM4ATags() that parses all standard iTunes atoms (title, artist,
album, album artist, date, genre, composer, comment, copyright, lyrics,
track/disc number) and freeform '----' atoms (ISRC, label, lyrics).
Fix two pre-existing bugs in the M4A atom traversal:
- findM4AIlstAtom: now tries moov>udta>meta>ilst first, then falls back
to moov>meta>ilst so files from Tidal/Qobuz/Apple Music are handled
- readM4AFreeformValue: 'name' atom payload is raw UTF-8 after 4-byte
flags, not a nested 'data' atom; fix reads it directly so ISRC/label
freeform tags are no longer silently dropped
Refactor extractLyricsFromM4A and extractCoverFromM4A to reuse the new
helpers (findM4AIlstAtom, readM4ADataAtomPayload) instead of duplicating
the atom traversal logic. Add extractAnyCoverArtWithHint M4A case that
previously returned a hardcoded 'not yet supported' error.
zarzet
c57c8a4267