fix post deletion cascade

src/main/java/com/openisle/repository/PostReadRepository.java

@@ -10,4 +10,5 @@ import java.util.Optional;
 public interface PostReadRepository extends JpaRepository<PostRead, Long> {
     Optional<PostRead> findByUserAndPost(User user, Post post);
     long countByUser(User user);
+    void deleteByPost(Post post);
 }

src/main/java/com/openisle/service/PostReadService.java

@@ -41,4 +41,9 @@ public class PostReadService {
                 .orElseThrow(() -> new IllegalArgumentException("User not found"));
         return postReadRepository.countByUser(user);
     }
+
+    @org.springframework.transaction.annotation.Transactional
+    public void deleteByPost(Post post) {
+        postReadRepository.deleteByPost(post);
+    }
 }

src/main/java/com/openisle/service/PostService.java

@@ -360,6 +360,7 @@ public class PostService {
         reactionRepository.findByPost(post).forEach(reactionRepository::delete);
         postSubscriptionRepository.findByPost(post).forEach(postSubscriptionRepository::delete);
         notificationRepository.deleteAll(notificationRepository.findByPost(post));
+        postReadService.deleteByPost(post);
         postRepository.delete(post);
     }