Fix TextField not accepting input by moving TextEditingController to state instead of recreating on every build

b0esche_cloud/lib/widgets/organization_settings_dialog.dart

@@ -36,13 +36,21 @@ class _OrganizationSettingsDialogState
   bool _isLoading = false;
   String? _error;
   List<User> _userSuggestions = [];
+  late final TextEditingController usernameController;
 
   @override
   void initState() {
     super.initState();
+    usernameController = TextEditingController();
     _loadData();
   }
 
+  @override
+  void dispose() {
+    usernameController.dispose();
+    super.dispose();
+  }
+
   Future<void> _loadData() async {
     if (!mounted) return;
     setState(() => _isLoading = true);
@@ -407,7 +415,6 @@ class _OrganizationSettingsDialogState
   }
 
   Widget _buildInviteTab() {
-    final usernameController = TextEditingController();
     String selectedRole = 'member';
 
     return Column(