fix: getMenusByRestaurant 하위 호환용 오버로드 메서드 추가

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Author: pooreumjung

src/main/java/ssu/eatssu/domain/menu/service/MenuService.java

@@ -38,6 +38,10 @@ private static void validateMenuRestaurant(Restaurant restaurant) {
         }
     }
 
+    public MenuRestaurantResponse getMenusByRestaurant(Restaurant restaurant) {
+        return getMenusByRestaurant(restaurant, null);
+    }
+
     public MenuRestaurantResponse getMenusByRestaurant(Restaurant restaurant, Language language) {
         validateMenuRestaurant(restaurant);