- Fixed download showing 'Song not found' when actually permission error
- Added permission error type detection in Go backend
- Android 13+ now requests both MANAGE_EXTERNAL_STORAGE and READ_MEDIA_AUDIO
- MANAGE_EXTERNAL_STORAGE opens Settings (system-level)
- READ_MEDIA_AUDIO shows dialog (app-level, resets on clear data)
- Proper permission check before showing 'granted' status