fix: add PaymentProvider field to prevent cross-gateway callback attacks

EPay allows users to switch payment methods (e.g. wxpay→alipay) during
checkout, causing callback rejection. Replace fragile blocklist guard
with a PaymentProvider field on TopUp and SubscriptionOrder that
identifies which gateway created the order.

controller/topup_waffo_pancake.go

@@ -159,13 +159,14 @@ func RequestWaffoPancakePay(c *gin.Context) {
 
 	tradeNo := fmt.Sprintf("WAFFO_PANCAKE-%d-%d-%s", id, time.Now().UnixMilli(), randstr.String(6))
 	topUp := &model.TopUp{
-		UserId:        id,
-		Amount:        normalizeWaffoPancakeTopUpAmount(req.Amount),
-		Money:         payMoney,
-		TradeNo:       tradeNo,
-		PaymentMethod: model.PaymentMethodWaffoPancake,
-		CreateTime:    time.Now().Unix(),
-		Status:        common.TopUpStatusPending,
+		UserId:          id,
+		Amount:          normalizeWaffoPancakeTopUpAmount(req.Amount),
+		Money:           payMoney,
+		TradeNo:         tradeNo,
+		PaymentMethod:   model.PaymentMethodWaffoPancake,
+		PaymentProvider: model.PaymentProviderWaffoPancake,
+		CreateTime:      time.Now().Unix(),
+		Status:          common.TopUpStatusPending,
 	}
 	if err := topUp.Insert(); err != nil {
 		logger.LogError(c.Request.Context(), fmt.Sprintf("Waffo Pancake 创建充值订单失败 user_id=%d trade_no=%s amount=%d error=%q", id, tradeNo, req.Amount, err.Error()))