feat: extension support (#78)

ui/flutter/lib/api/model/update_extension_settings.dart

@@ -0,0 +1,16 @@
+import 'package:json_annotation/json_annotation.dart';
+
+part 'update_extension_settings.g.dart';
+
+@JsonSerializable()
+class UpdateExtensionSettings {
+  Map<String, dynamic> settings;
+
+  UpdateExtensionSettings({
+    required this.settings,
+  });
+
+  factory UpdateExtensionSettings.fromJson(Map<String, dynamic> json) =>
+      _$UpdateExtensionSettingsFromJson(json);
+  Map<String, dynamic> toJson() => _$UpdateExtensionSettingsToJson(this);
+}