Add spacing between role selection and dropdown in organization settings dialog

b0esche_cloud/lib/widgets/organization_settings_dialog.dart

@@ -551,6 +551,7 @@ class _OrganizationSettingsDialogState
                 },
               ),
             ),
+            const SizedBox(height: 16),
             DropdownButtonFormField<String>(
               initialValue: selectedRole,
               items: ['admin', 'member'].map((role) {