[BE] 코스 전체 조회시 불필요하게 실행되는 쿼리 제거

course_stack 조회 쿼리 한 번에 실행되도록 수정

 select
        c1_0.course_id,
        c1_0.course_stack_id,
        c1_0.created_at,
        c1_0.modified_at,
        c1_0.stack_id
    from
        course_stack c1_0
    where
        c1_0.course_id in (39,34,37,32,35,30,36,31,33,27,29,28,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL)

backend/src/main/java/com/bootme/course/service/CourseService.java

@@ -89,10 +89,8 @@ private CourseDetailResponse createCourseDetailResponse(Course course, boolean i
     }
 
     @Transactional(readOnly = true)
-    public Page<CourseResponse> findAll(Long memberId, int page, int size, String sort,
-                                        MultiValueMap<String, String> params) {
+    public Page<CourseResponse> findAll(Long memberId, int page, int size, String sort, MultiValueMap<String, String> params) {
         boolean isLogin = authService.validateLogin(memberId);
-
         Predicate combinedPredicate = getCombinedPredicate(params);
 
         return getCoursePage(page, size, sort, combinedPredicate)
@@ -101,7 +99,9 @@ public Page<CourseResponse> findAll(Long memberId, int page, int size, String so
 
     private CourseResponse createCourseResponse(Course course, boolean isLogin, Long memberId) {
         boolean isBookmarked = isLogin && courseBookmarkRepository.existsByBookmark_Member_IdAndCourse_Id(memberId, course.getId());
-        List<Stack> stacks = courseStackRepository.findStacksByCourseId(course.getId());
+        List<Stack> stacks = course.getCourseStacks().stream()
+                .map(CourseStack::getStack)
+                .toList();
         return CourseResponse.of(course, stacks, isBookmarked);
     }