feat: 카드 응답에 카드사/매입사 정보 추가

- card_company (position 9)
- acquirer_name (position 10)
- approval_datetime, card_no, merchant_no 등
- Flask API 응답과 동일한 필드명 사용

PaymentBridge.cs

@@ -269,13 +269,26 @@ namespace PaymentBridge
                 Thread.Sleep(500);
                 string retCode = GetRetData(2);
                 string retMsg = GetRetData(3);
+                string approvalDatetime = GetRetData(4);
+                string cardNo = GetRetData(5);
                 string approvalNo = GetRetData(6);
+                string retAmount = GetRetData(7);
+                string merchantNo = GetRetData(8);
+                string cardCompany = GetRetData(9);
+                string acquirerName = GetRetData(10);
                 
                 return json.Serialize(new {
                     ok = retCode == "0000",
                     code = retCode,
                     message = retMsg,
                     approvalNo = approvalNo,
+                    approval_no = approvalNo,
+                    card_company = cardCompany,
+                    acquirer_name = acquirerName,
+                    approval_datetime = approvalDatetime,
+                    card_no = cardNo,
+                    merchant_no = merchantNo,
+                    ret_amount = retAmount,
                     cmd = cmd
                 });
             }