fix: 正确获取BepUsdt钱包地址

BepUsdt API返回的钱包地址在token字段中，不是address字段

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/internal/api/handlers/payment.go

@@ -157,34 +157,8 @@ func (h *PaymentHandler) CreatePayment(c *gin.Context) {
 	token, _ := data["token"].(string)
 	paymentURL, _ := data["payment_url"].(string)
 
-	// 尝试多个可能的字段名获取钱包地址
-	var walletAddress string
-	addressFields := []string{"address", "wallet_address", "to_address", "payment_address", "deposit_address", "receiver_address"}
-	for _, field := range addressFields {
-		if addr, ok := data[field].(string); ok && addr != "" {
-			walletAddress = addr
-			log.Printf("[BepUsdt] found wallet address in field '%s': %s", field, addr)
-			break
-		}
-	}
-
-	// 如果没有直接获取到钱包地址，尝试从payment_url解析
-	if walletAddress == "" && paymentURL != "" {
-		// payment_url格式可能是: usdt:TRC20地址?amount=xxx 或直接是钱包地址
-		if strings.HasPrefix(paymentURL, "usdt:") || strings.HasPrefix(paymentURL, "USDT:") {
-			parts := strings.SplitN(paymentURL, ":", 2)
-			if len(parts) > 1 {
-				// 移除查询参数
-				addrPart := strings.SplitN(parts[1], "?", 2)[0]
-				walletAddress = strings.TrimSpace(addrPart)
-				log.Printf("[BepUsdt] parsed wallet address from payment_url: %s", walletAddress)
-			}
-		} else if len(paymentURL) >= 30 && !strings.Contains(paymentURL, "://") {
-			// 可能直接就是钱包地址
-			walletAddress = paymentURL
-			log.Printf("[BepUsdt] using payment_url as wallet address: %s", walletAddress)
-		}
-	}
+	// 钱包地址在token字段中
+	walletAddress := token
 
 	log.Printf("[BepUsdt] payment data: trade_id=%s, token=%s, payment_url=%s, wallet_address=%s", tradeID, token, paymentURL, walletAddress)