🐛 fix: 쿠폰 및 포인트 적용 후의 값을 DB에 저장하도록 수정

Author: tl1l1l1s

src/main/java/com/jajaja/domain/order/service/OrderCommandServiceImpl.java

@@ -113,7 +113,7 @@ public OrderPrepareResponseDto prepareOrder(Long memberId, OrderPrepareRequestDt
                 .paymentMethod(PaymentMethod.NORMAL)
                 .orderId(orderId)
                 .orderName(orderName)
-                .totalAmount(totalAmount)
+                .totalAmount(finalAmount)
                 .member(member)
                 .delivery(delivery)
                 .coupon(coupon)