Add Hungarian English language switcher

lib/data.dart

@@ -122,6 +122,7 @@ class AppJsonStore {
         final settings = AppSettings(
           people: defaultPeople(),
           themeId: 'sage',
+          languageCode: defaultLanguageCode,
           googleConnections: defaultGoogleConnections(),
           syncedEvents: const [],
           todoSuggestions: const [],
@@ -139,6 +140,7 @@ class AppJsonStore {
       return AppSettings(
         people: defaultPeople(),
         themeId: 'sage',
+        languageCode: defaultLanguageCode,
         googleConnections: defaultGoogleConnections(),
         syncedEvents: const [],
         todoSuggestions: const [],
@@ -160,6 +162,7 @@ class AppSettings {
   AppSettings({
     required this.people,
     required this.themeId,
+    required this.languageCode,
     required this.googleConnections,
     required this.syncedEvents,
     required this.todoSuggestions,
@@ -169,6 +172,7 @@ class AppSettings {
 
   final List<Person> people;
   final String themeId;
+  final String languageCode;
   final List<GoogleCalendarConnection> googleConnections;
   final List<CalendarEvent> syncedEvents;
   final List<String> todoSuggestions;
@@ -191,6 +195,7 @@ class AppSettings {
             )
           : defaultPeople(),
       themeId: json['themeId'] as String? ?? 'sage',
+      languageCode: json['languageCode'] == 'en' ? 'en' : defaultLanguageCode,
       googleConnections: rawConnections is List
           ? rawConnections
                 .whereType<Map<String, dynamic>>()
@@ -218,6 +223,7 @@ class AppSettings {
 
   Map<String, dynamic> toJson() => {
     'themeId': themeId,
+    'languageCode': languageCode,
     'people': people.map((person) => person.toJson()).toList(),
     'googleConnections': googleConnections
         .map((connection) => connection.toJson())