- Add lyrics mode setting (embed/external/both) for saving lyrics
- Implement SaveLRCFile() in Go backend for all providers (Tidal, Qobuz, Amazon)
- Fix locale parsing in app.dart to handle country codes (e.g., pt_PT -> Locale('pt', 'PT'))
- Change Portuguese label from Portugal to Brasil in language settings
- Add locale field to AppSettings model with 'system' default
- Add Language section in Appearance settings page
- Support System Default, English, and Indonesian options
- App language changes take effect immediately
- Add localization strings for language selector