feat: 订单自动过期-查看时检查并取消超时订单，收银台倒计时结束自动取消

backend/internal/api/handlers/payment.go

@@ -39,7 +39,7 @@ func (h *PaymentHandler) CreatePayment(c *gin.Context) {
 	orderID, _ := strconv.Atoi(c.Param("id"))
 
 	var order models.Order
-	if err := utils.DB.Where("id = ? AND user_id = ?", orderID, userID).First(&order).Error; err != nil {
+	if err := utils.DB.Preload("OrderItems").Where("id = ? AND user_id = ?", orderID, userID).First(&order).Error; err != nil {
 		c.JSON(http.StatusNotFound, gin.H{"error": "Order not found"})
 		return
 	}
@@ -49,6 +49,20 @@ func (h *PaymentHandler) CreatePayment(c *gin.Context) {
 		return
 	}
 
+	if order.PaymentExpiresAt != nil && time.Now().After(*order.PaymentExpiresAt) {
+		tx := utils.DB.Begin()
+		tx.Model(&order).Update("status", models.OrderStatusCancelled)
+		for _, item := range order.OrderItems {
+			var inventory models.Inventory
+			if err := tx.Where("product_id = ?", item.ProductID).First(&inventory).Error; err == nil {
+				tx.Model(&inventory).UpdateColumn("quantity", inventory.Quantity+item.Quantity)
+			}
+		}
+		tx.Commit()
+		c.JSON(http.StatusBadRequest, gin.H{"error": "支付已超时，订单已取消"})
+		return
+	}
+
 	var channels []models.PaymentChannel
 	utils.DB.Where("is_enabled = ? AND type = ?", true, "bepusdt").Order("sort_order ASC").Find(&channels)
 	if len(channels) == 0 {
@@ -169,15 +183,21 @@ func (h *PaymentHandler) CreatePayment(c *gin.Context) {
 	}
 
 	var remainingSeconds int64
+	var expiresAt *time.Time
 	if expiration > 0 {
 		remainingSeconds = expiration - time.Now().Unix()
 		if remainingSeconds < 0 {
 			remainingSeconds = 0
 		}
+		if remainingSeconds > 0 {
+			t := time.Now().Add(time.Duration(remainingSeconds) * time.Second)
+			expiresAt = &t
+		}
 	}
 
 	utils.DB.Model(&order).Updates(map[string]interface{}{
-		"payment_method": "bepusdt",
+		"payment_method":      "bepusdt",
+		"payment_expires_at":  expiresAt,
 	})
 
 	paymentInfo := map[string]interface{}{