feat(go): verification early-abort in fallback + album metadata from tracks

- DownloadWithExtensionFallback now immediately surfaces verification_required
  when any provider needs verification (availability + download stages),
  instead of letting later providers mask it
- classifyDownloadErrorType treats 'session is not authenticated' as
  verification_required (Go + Dart side)
- parseExtensionAlbumValue.withTrackFallbacks() derives album artist,
  release date, and audio traits from tracks when album-level missing
- albumAudioTraitsFromTracks detects dolby_atmos/hi_res_lossless/lossless
  from per-track audio_quality/audio_modes fields
- parseBitDepthSampleRate parses '24bit/96kHz' style quality labels

lib/utils/extension_auth_launcher.dart

@@ -11,6 +11,7 @@ bool isExtensionVerificationRequired(Object error) {
       message.contains('verification required') ||
       message.contains('needsverification') ||
       message.contains('needs verification') ||
+      message.contains('session is not authenticated') ||
       message.contains('unauthorized') ||
       message.contains('precondition required') ||
       _containsHttpStatusCode(message, '401') ||