fix(l10n): Update Korean language code from 'kr' to 'ko'

lib/features/profile/views/app_customization_page.dart

@@ -1669,7 +1669,7 @@ class AppCustomizationPage extends ConsumerWidget {
         return AppLocalizations.of(context)!.russian;
       case 'zh':
         return AppLocalizations.of(context)!.chinese;
-      case 'kr':
+      case 'ko':
         return AppLocalizations.of(context)!.korean;
       default:
         return AppLocalizations.of(context)!.system;
@@ -1905,8 +1905,8 @@ class AppCustomizationPage extends ConsumerWidget {
               ),
               ListTile(
                 title: Text(AppLocalizations.of(context)!.korean),
-                trailing: current == 'kr' ? const Icon(Icons.check) : null,
-                onTap: () => Navigator.pop(context, 'kr'),
+                trailing: current == 'ko' ? const Icon(Icons.check) : null,
+                onTap: () => Navigator.pop(context, 'ko'),
               ),
               const SizedBox(height: Spacing.sm),
             ],