feat: WiFi-only download mode

- Add network mode setting (any/wifi_only) in settings model
- Add connectivity check in download queue processor
- Downloads pause automatically when on mobile data (if wifi_only enabled)
- Add UI toggle in Download Settings page
- Add localization strings for network mode setting
- Bump version to 3.3.6+71

lib/models/settings.dart

@@ -35,6 +35,7 @@ class AppSettings {
   final String tidalHighFormat; // Format for Tidal HIGH quality: 'mp3_320' or 'opus_128'
   final bool useAllFilesAccess; // Android 13+ only: enable MANAGE_EXTERNAL_STORAGE
   final bool autoExportFailedDownloads; // Auto export failed downloads to TXT file
+  final String downloadNetworkMode; // 'any' = WiFi + Mobile, 'wifi_only' = WiFi only
 
   const AppSettings({
     this.defaultService = 'tidal',
@@ -68,6 +69,7 @@ class AppSettings {
     this.tidalHighFormat = 'mp3_320',
     this.useAllFilesAccess = false,
     this.autoExportFailedDownloads = false,
+    this.downloadNetworkMode = 'any',
   });
 
   AppSettings copyWith({
@@ -103,6 +105,7 @@ class AppSettings {
     String? tidalHighFormat,
     bool? useAllFilesAccess,
     bool? autoExportFailedDownloads,
+    String? downloadNetworkMode,
   }) {
     return AppSettings(
       defaultService: defaultService ?? this.defaultService,
@@ -136,6 +139,7 @@ class AppSettings {
       tidalHighFormat: tidalHighFormat ?? this.tidalHighFormat,
       useAllFilesAccess: useAllFilesAccess ?? this.useAllFilesAccess,
       autoExportFailedDownloads: autoExportFailedDownloads ?? this.autoExportFailedDownloads,
+      downloadNetworkMode: downloadNetworkMode ?? this.downloadNetworkMode,
     );
   }
 

lib/models/settings.g.dart

@@ -41,6 +41,7 @@ AppSettings _$AppSettingsFromJson(Map<String, dynamic> json) => AppSettings(
   useAllFilesAccess: json['useAllFilesAccess'] as bool? ?? false,
   autoExportFailedDownloads:
       json['autoExportFailedDownloads'] as bool? ?? false,
+  downloadNetworkMode: json['downloadNetworkMode'] as String? ?? 'any',
 );
 
 Map<String, dynamic> _$AppSettingsToJson(AppSettings instance) =>
@@ -76,4 +77,5 @@ Map<String, dynamic> _$AppSettingsToJson(AppSettings instance) =>
       'tidalHighFormat': instance.tidalHighFormat,
       'useAllFilesAccess': instance.useAllFilesAccess,
       'autoExportFailedDownloads': instance.autoExportFailedDownloads,
+      'downloadNetworkMode': instance.downloadNetworkMode,
     };