fix(支付): 修复金额计算精度问题

在epayPayment和CryptoSaaSPayment方法中，对转换后的金额进行四舍五入保留两位小数处理，确保支付金额精度准确

internal/logic/public/portal/purchaseCheckoutLogic.go

@@ -275,6 +275,7 @@ func (l *PurchaseCheckoutLogic) epayPayment(config *payment.Payment, info *order
     if err != nil {
         return "", err
     }
+    amount = math.Round(amount*100) / 100
 
 	// Build notification URL for payment status callbacks
 	notifyUrl := ""
@@ -317,6 +318,7 @@ func (l *PurchaseCheckoutLogic) CryptoSaaSPayment(config *payment.Payment, info
     if err != nil {
         return "", err
     }
+    amount = math.Round(amount*100) / 100
 
 	// Build notification URL for payment status callbacks
 	notifyUrl := ""