feat: 공개 코스 삭제 시 FK 제약 조건 해소

- Record.publicCourse null 처리 (기존 엔티티 관계 활용)
- Scrap 행 삭제 (기존 repository 메서드 활용)
- deleteAllInBatch → deleteAll 변경 (Hibernate ActionQueue 순서 보장)

Author: thingineeer

src/main/java/org/runnect/server/publicCourse/service/PublicCourseService.java

@@ -13,6 +13,7 @@
 import org.runnect.server.common.exception.PermissionDeniedException;
 import org.runnect.server.common.module.convert.CoordinatePathConverter;
 import org.runnect.server.course.entity.Course;
+import org.runnect.server.record.entity.Record;
 import org.runnect.server.course.repository.CourseRepository;
 import org.runnect.server.publicCourse.dto.request.CreatePublicCourseRequestDto;
 import org.runnect.server.publicCourse.dto.request.DeletePublicCoursesRequestDto;
@@ -365,7 +366,16 @@ public DeletePublicCoursesResponseDto deletePublicCourses(
         //삭제전 course의 isPrivate update
         publicCourses.forEach(publicCourse -> publicCourse.getCourse().retrieveCourse());
 
-        publicCourseRepository.deleteAllInBatch(publicCourses);
+        // FK 제약 조건 해소: Record.public_course_id (NULLABLE) → null 처리
+        publicCourses.forEach(publicCourse ->
+            publicCourse.getRecords().forEach(Record::setPublicCourseNull)
+        );
+
+        // FK 제약 조건 해소: Scrap.public_course_id (NOT NULL) → 행 삭제
+        scrapRepository.deleteByPublicCourseIn(publicCourses);
+
+        // deleteAll: Hibernate ActionQueue가 UPDATE → DELETE 순서 보장
+        publicCourseRepository.deleteAll(publicCourses);
 
         return DeletePublicCoursesResponseDto.from(publicCourses.size());
     }