add

backend/src/main/java/com/flower/confession/BarrageRepository.java

@@ -0,0 +1,9 @@
+package com.flower.confession;
+
+import org.springframework.data.jpa.repository.JpaRepository;
+
+import java.util.List;
+
+public interface BarrageRepository extends JpaRepository<Barrage, Long> {
+    List<Barrage> findByConfessionIdOrderByCreatedAtAsc(Long confessionId);
+}