Fix field size and improve comments based on code review feedback

Co-authored-by: hsluoyz <3787410+hsluoyz@users.noreply.github.com>

object/order_pay.go

@@ -264,9 +264,12 @@ func PayOrder(providerName, host, paymentEnv string, order *Order, lang string)
 
 		Products:            productNames,
 		ProductsDisplayName: reqProductDisplayName,
-		Detail:              reqProductDescription,
-		Currency:            order.Currency,
-		Price:               order.Price,
+		// Old fields for backward compatibility - contain comma-separated product names/display names
+		ProductName:        reqProductName,
+		ProductDisplayName: reqProductDisplayName,
+		Detail:             reqProductDescription,
+		Currency:           order.Currency,
+		Price:              order.Price,
 
 		User:       user.Name,
 		Order:      order.Name,

object/payment.go

@@ -33,9 +33,12 @@ type Payment struct {
 	// Product Info
 	Products            []string `xorm:"varchar(1000)" json:"products"`
 	ProductsDisplayName string   `xorm:"varchar(1000)" json:"productsDisplayName"`
-	Detail              string   `xorm:"varchar(255)" json:"detail"`
-	Currency            string   `xorm:"varchar(100)" json:"currency"`
-	Price               float64  `json:"price"`
+	// Old fields kept for backward compatibility - contain comma-separated product names/display names
+	ProductName        string  `xorm:"varchar(1000)" json:"productName"`
+	ProductDisplayName string  `xorm:"varchar(1000)" json:"productDisplayName"`
+	Detail             string  `xorm:"varchar(255)" json:"detail"`
+	Currency           string  `xorm:"varchar(100)" json:"currency"`
+	Price              float64 `json:"price"`
 
 	// Payer Info
 	User         string `xorm:"varchar(100)" json:"user"`