feat: add Deezer download service, Qobuz squid.wtf fallback, update changelog

lib/providers/extension_provider.dart

@@ -811,7 +811,7 @@ class ExtensionNotifier extends Notifier<ExtensionState> {
       }
     }
 
-    for (final provider in const ['tidal', 'qobuz', 'amazon']) {
+    for (final provider in const ['tidal', 'qobuz', 'amazon', 'deezer']) {
       if (!result.contains(provider)) {
         result.add(provider);
       }
@@ -880,7 +880,7 @@ class ExtensionNotifier extends Notifier<ExtensionState> {
   }
 
   List<String> getAllDownloadProviders() {
-    final providers = ['tidal', 'qobuz', 'amazon'];
+    final providers = ['tidal', 'qobuz', 'amazon', 'deezer'];
     for (final ext in state.extensions) {
       if (ext.enabled && ext.hasDownloadProvider) {
         providers.add(ext.id);

lib/screens/settings/download_settings_page.dart

@@ -23,7 +23,7 @@ class DownloadSettingsPage extends ConsumerStatefulWidget {
 }
 
 class _DownloadSettingsPageState extends ConsumerState<DownloadSettingsPage> {
-  static const _builtInServices = ['tidal', 'qobuz', 'amazon'];
+  static const _builtInServices = ['tidal', 'qobuz', 'amazon', 'deezer'];
   static const _songLinkRegions = [
     'AD',
     'AE',
@@ -2039,7 +2039,7 @@ class _ServiceSelector extends ConsumerWidget {
   @override
   Widget build(BuildContext context, WidgetRef ref) {
     final extState = ref.watch(extensionProvider);
-    final builtInServiceIds = ['tidal', 'qobuz', 'amazon', 'youtube'];
+    final builtInServiceIds = ['tidal', 'qobuz', 'amazon', 'deezer', 'youtube'];
 
     final extensionProviders = extState.extensions
         .where((e) => e.enabled && e.hasDownloadProvider)

lib/widgets/download_service_picker.dart

@@ -78,6 +78,17 @@ const _builtInServices = [
       ),
     ],
   ),
+  BuiltInService(
+    id: 'deezer',
+    label: 'Deezer',
+    qualityOptions: [
+      QualityOption(
+        id: 'FLAC',
+        label: 'FLAC Lossless',
+        description: '16-bit / 44.1kHz (CD Quality)',
+      ),
+    ],
+  ),
   BuiltInService(
     id: 'youtube',
     label: 'YouTube',