fix: back gesture freeze on Android 13+ and add album folder structure setting

- Add PopScope with canPop:true to all settings pages for predictive back gesture support
- Change settings navigation to use PageRouteBuilder instead of MaterialPageRoute
- Add album folder structure setting (artist_album vs album_only)
- Fix extension search result parsing to handle both array and object formats
- Update CHANGELOG

Fixes back gesture freeze issue on OnePlus and other Android 13+ devices with gesture navigation

lib/models/settings.dart

@@ -28,6 +28,7 @@ class AppSettings {
   final bool useExtensionProviders; // Use extension providers for downloads when available
   final String? searchProvider; // null/empty = default (Deezer/Spotify), otherwise extension ID
   final bool separateSingles; // Separate singles/EPs into their own folder
+  final String albumFolderStructure; // artist_album or album_only
   final bool showExtensionStore; // Show Extension Store tab in navigation
 
   const AppSettings({
@@ -55,6 +56,7 @@ class AppSettings {
     this.useExtensionProviders = true, // Default: use extensions when available
     this.searchProvider, // Default: null (use Deezer/Spotify)
     this.separateSingles = false, // Default: disabled
+    this.albumFolderStructure = 'artist_album', // Default: Albums/Artist/Album
     this.showExtensionStore = true, // Default: show store
   });
 
@@ -82,7 +84,9 @@ class AppSettings {
     bool? enableLogging,
     bool? useExtensionProviders,
     String? searchProvider,
+    bool clearSearchProvider = false, // Set to true to clear searchProvider to null
     bool? separateSingles,
+    String? albumFolderStructure,
     bool? showExtensionStore,
   }) {
     return AppSettings(
@@ -108,8 +112,9 @@ class AppSettings {
       metadataSource: metadataSource ?? this.metadataSource,
       enableLogging: enableLogging ?? this.enableLogging,
       useExtensionProviders: useExtensionProviders ?? this.useExtensionProviders,
-      searchProvider: searchProvider ?? this.searchProvider,
+      searchProvider: clearSearchProvider ? null : (searchProvider ?? this.searchProvider),
       separateSingles: separateSingles ?? this.separateSingles,
+      albumFolderStructure: albumFolderStructure ?? this.albumFolderStructure,
       showExtensionStore: showExtensionStore ?? this.showExtensionStore,
     );
   }

lib/models/settings.g.dart

@@ -32,6 +32,7 @@ AppSettings _$AppSettingsFromJson(Map<String, dynamic> json) => AppSettings(
   useExtensionProviders: json['useExtensionProviders'] as bool? ?? true,
   searchProvider: json['searchProvider'] as String?,
   separateSingles: json['separateSingles'] as bool? ?? false,
+  albumFolderStructure: json['albumFolderStructure'] as String? ?? 'artist_album',
   showExtensionStore: json['showExtensionStore'] as bool? ?? true,
 );
 
@@ -61,5 +62,6 @@ Map<String, dynamic> _$AppSettingsToJson(AppSettings instance) =>
       'useExtensionProviders': instance.useExtensionProviders,
       'searchProvider': instance.searchProvider,
       'separateSingles': instance.separateSingles,
+      'albumFolderStructure': instance.albumFolderStructure,
       'showExtensionStore': instance.showExtensionStore,
     };