feature: 쿠폰 확인 실패 시 재시도 메커니즘 추가

- 재시도 스케줄링을 처리하기 위해 `FailedEventStore` 도입.
- `CouponUsageEventListener`에 예외 처리 로직을 추가하여 락 충돌 및 기타 오류 발생 시 재시도 수행.
- 쿠폰 사용 확인 프로세스의 안정성을 강화.

Author: yeonjiyeon

apps/commerce-api/src/main/java/com/loopers/application/coupon/CouponUsageEventListener.java

@@ -1,8 +1,10 @@
 package com.loopers.application.coupon;
 
+import com.loopers.application.event.FailedEventStore;
 import com.loopers.application.payment.PaymentEvent.PaymentCompletedEvent;
 import com.loopers.domain.coupon.CouponService;
 import lombok.RequiredArgsConstructor;
+import org.springframework.orm.ObjectOptimisticLockingFailureException;
 import org.springframework.stereotype.Component;
 import org.springframework.transaction.annotation.Transactional;
 import org.springframework.transaction.event.TransactionPhase;
@@ -12,13 +14,22 @@
 @RequiredArgsConstructor
 public class CouponUsageEventListener {
   private final CouponService couponService;
+  private final FailedEventStore failedEventStore;
 
   @TransactionalEventListener(phase = TransactionPhase.AFTER_COMMIT)
   @Transactional
   public void handlePaymentCompletedEvent(PaymentCompletedEvent event) {
 
-    if (event.couponId() != null) {
+    if (event.couponId() == null) return;
+
+    try {
       couponService.confirmCouponUsage(event.couponId());
+
+    } catch (ObjectOptimisticLockingFailureException e) {
+      failedEventStore.scheduleRetry(event, "Coupon Lock Conflict on Confirmation");
+
+    } catch (Exception e) {
+      failedEventStore.scheduleRetry(event, "Coupon confirmation error: " + e.getMessage());
     }
   }
 }

apps/commerce-api/src/main/java/com/loopers/application/payment/PaymentEvent.java

@@ -1,5 +1,7 @@
 package com.loopers.application.payment;
 
+import com.loopers.domain.event.DomainEvent;
+
 public class PaymentEvent {
   public record PaymentRequestedEvent(
       Long orderId,
@@ -12,7 +14,7 @@ public record PaymentCompletedEvent(
       Long paymentId,
       boolean isSuccess,
       Long couponId
-  ) {}
+  ) implements DomainEvent {}
 
   public record PaymentRequestFailedEvent(
       Long orderId,