feat(audio): add WAV and AIFF support + settings-style metadata menu

WAV/AIFF: library scan, quality probe, native tag read/write via embedded ID3 chunk (RIFF id3 / AIFF ID3), cover art, ReadFileMetadata, ExtractLyrics, and FLAC<->WAV/AIFF conversion (PCM, bit-depth preserved via ffprobe). Treat WAV/AIFF as lossless across all convert sheets (no bitrate picker, Lossless labels) via isLosslessConversionTarget. Native MIME maps for SAF. Redesign the track metadata three-dot menu to a settings-style grouped card with a single divider above Share.

lib/utils/path_match_keys.dart

@@ -19,6 +19,8 @@ const _audioExtensions = <String>[
   '.opus',
   '.ogg',
   '.wav',
+  '.aiff',
+  '.aif',
   '.aac',
 ];