fix(mobile): use JSON maps for nested config compatibility defaults

mobile/lib/utils/openapi_patching.dart

@@ -34,7 +34,9 @@ final Map<String, Map<String, Object?>> openApiPatches = {
       lightStyle: 'https://tiles.immich.cloud/v1/style/light.json',
       darkStyle: 'https://tiles.immich.cloud/v1/style/dark.json',
     ).toJson(),
-    'ffmpeg': PublicConfigFFmpegDto(realtime: PublicConfigFFmpegRealtimeDto(enabled: false)).toJson(),
+    'ffmpeg': {
+      'realtime': {'enabled': false},
+    },
   },
   'ServerConfigDto': {
     'mapLightStyleUrl': 'https://tiles.immich.cloud/v1/style/light.json',
@@ -53,7 +55,11 @@ final Map<String, Map<String, Object?>> openApiPatches = {
   'PeopleResponse': {'updateStrategy': 'everyone'},
   'PersonResponseDto': {'otherPeople': const [], 'sharedBy': const [], 'sharedWith': const []},
   'ServerVersionResponseDto': {'featureLevel': 0},
-  'UserConfigDto': {'notifications': UserConfigNotificationsDto(smtp: UserConfigSmtpDto(enabled: false)).toJson()},
+  'UserConfigDto': {
+    'notifications': {
+      'smtp': {'enabled': false},
+    },
+  },
   'WorkflowResponseDto': {'logging': false},
 };
 

mobile/test/modules/utils/openapi_patching_test.dart

@@ -7,7 +7,7 @@ import 'package:openapi/api.dart';
 void main() {
   group('Test OpenApi Patching', () {
     test('older public config deserializes with map and video defaults', () {
-      final config = PublicConfigDto.fromJson({
+      final config = PublicConfigDto.fromJson(<String, dynamic>{
         'oauth': {'autoLaunch': false, 'buttonText': 'Login', 'enabled': false},
         'passwordLogin': {'enabled': true},
         'server': {'loginPageMessage': ''},
@@ -19,7 +19,7 @@ void main() {
     });
 
     test('public config keeps explicit server map and video settings', () {
-      final config = PublicConfigDto.fromJson({
+      final config = PublicConfigDto.fromJson(<String, dynamic>{
         'oauth': {'autoLaunch': false, 'buttonText': 'Login', 'enabled': false},
         'passwordLogin': {'enabled': true},
         'server': {'loginPageMessage': ''},