feat(tidal): add native AAC 320kbps quality option

- Add HIGH quality option (AAC 320kbps) for Tidal downloads
- Download directly as M4A without FLAC conversion
- Embed metadata to M4A using EmbedM4AMetadata()
- Skip M4A to FLAC conversion in download provider for HIGH quality
- Add AAC 320kbps option in settings page (Tidal only)
- Add HIGH quality option in download service picker

lib/providers/download_queue_provider.dart

@@ -1980,9 +1980,14 @@ class DownloadQueueNotifier extends Notifier<DownloadQueueState> {
         }
 
         if (filePath != null && filePath.endsWith('.m4a')) {
-          _log.d(
-            'M4A file detected (Hi-Res DASH stream), attempting conversion to FLAC...',
-          );
+          // For HIGH quality (native AAC 320kbps), skip M4A to FLAC conversion
+          if (quality == 'HIGH') {
+            _log.i('Native AAC 320kbps download (HIGH quality), keeping M4A file');
+            actualQuality = 'AAC 320kbps';
+          } else {
+            _log.d(
+              'M4A file detected (Hi-Res DASH stream), attempting conversion to FLAC...',
+            );
 
           try {
             final file = File(filePath);
@@ -2084,6 +2089,7 @@ class DownloadQueueNotifier extends Notifier<DownloadQueueState> {
           } catch (e) {
             _log.w('FFmpeg conversion process failed: $e, keeping M4A file');
           }
+          } // end else (not HIGH quality)
         }
 
         final itemAfterDownload = state.items.firstWhere(

lib/screens/settings/download_settings_page.dart

@@ -94,6 +94,7 @@ class _DownloadSettingsPageState extends ConsumerState<DownloadSettingsPage> {
     final topPadding = MediaQuery.of(context).padding.top;
     
     final isBuiltInService = _builtInServices.contains(settings.defaultService);
+    final isTidalService = settings.defaultService == 'tidal';
 
     return PopScope(
       canPop: true,
@@ -215,8 +216,19 @@ class _DownloadSettingsPageState extends ConsumerState<DownloadSettingsPage> {
                       onTap: () => ref
                           .read(settingsProvider.notifier)
                           .setAudioQuality('HI_RES_LOSSLESS'),
-                      showDivider: settings.enableLossyOption,
+                      showDivider: isTidalService || settings.enableLossyOption,
                     ),
+                    // Native AAC 320kbps option (Tidal only)
+                    if (isTidalService)
+                      _QualityOption(
+                        title: 'AAC 320kbps',
+                        subtitle: 'Native AAC (no conversion)',
+                        isSelected: settings.audioQuality == 'HIGH',
+                        onTap: () => ref
+                            .read(settingsProvider.notifier)
+                            .setAudioQuality('HIGH'),
+                        showDivider: settings.enableLossyOption,
+                      ),
                     if (settings.enableLossyOption)
                       _QualityOption(
                         title: context.l10n.qualityLossy,

lib/widgets/download_service_picker.dart

@@ -27,6 +27,7 @@ const _builtInServices = [
       QualityOption(id: 'LOSSLESS', label: 'FLAC Lossless', description: '16-bit / 44.1kHz'),
       QualityOption(id: 'HI_RES', label: 'Hi-Res FLAC', description: '24-bit / up to 96kHz'),
       QualityOption(id: 'HI_RES_LOSSLESS', label: 'Hi-Res FLAC Max', description: '24-bit / up to 192kHz'),
+      QualityOption(id: 'HIGH', label: 'AAC 320kbps', description: 'Native AAC (no conversion)'),
     ],
   ),
   BuiltInService(
@@ -257,6 +258,8 @@ class _DownloadServicePickerState extends ConsumerState<DownloadServicePicker> {
         return Icons.high_quality;
       case 'LOSSLESS':
         return Icons.music_note;
+      case 'HIGH':
+        return Icons.aod;
       case 'MP3_320':
       case 'MP3':
       case 'LOSSY':