feat(pay): 添加PingPong支付回调处理功能

- 新增CallbackController接收并处理PingPong支付回调通知
- 实现回调签名验证逻辑
- 添加支付结果页面展示功能，支持成功、失败、审核中等状态显示
- 创建CallbackService接口及实现类处理回调业务逻辑
- 新增账单地址DTO(BillingDTO)用于风险信息传输
- 添加航空信息DTO(AirlineDTO)和租车信息DTO(CarRentalDTO)作为扩展风险数据结构
- 完善Checkout请求DTO字段校验规则，增强数据安全性
- 实现订单状态映射与更新机制，确保支付状态同步准确
- 记录回调处理日志便于问题追踪与审计

mt-pay/src/main/java/com/mtkj/mtpay/dto/request/CheckoutRequestDTO.java

@@ -0,0 +1,80 @@
+package com.mtkj.mtpay.dto.request;
+
+import com.mtkj.mtpay.dto.RiskInfoDTO;
+import jakarta.validation.Valid;
+import jakarta.validation.constraints.*;
+import lombok.Data;
+
+import java.io.Serializable;
+
+/**
+ * Checkout接口请求DTO
+ */
+@Data
+public class CheckoutRequestDTO implements Serializable {
+    
+    @NotBlank(message = "商户店铺编号不能为空")
+    @Size(max = 64, message = "商户店铺编号长度不能超过64")
+    private String accId;
+    
+    @NotBlank(message = "交易金额不能为空")
+    @Pattern(regexp = "^\\d+(\\.\\d{2})?$", message = "交易金额格式不正确，需保留两位小数")
+    @Size(max = 12, message = "交易金额长度不能超过12")
+    private String amount;
+    
+    @NotBlank(message = "交易币种不能为空")
+    @Size(min = 3, max = 3, message = "交易币种必须为3位ISO 4217币种代码")
+    private String currency;
+    
+    @NotBlank(message = "商户订单号不能为空")
+    @Size(max = 64, message = "商户订单号长度不能超过64")
+    private String merchantTransactionId;
+    
+    @NotBlank(message = "交易类型不能为空")
+    @Pattern(regexp = "^(SALE|AUTH)$", message = "交易类型必须为SALE或AUTH")
+    private String paymentType;
+    
+    @Size(max = 64, message = "支付方式长度不能超过64")
+    private String paymentBrand;
+    
+    @NotBlank(message = "结果重定向URL不能为空")
+    @Size(max = 255, message = "结果重定向URL长度不能超过255")
+    private String shopperResultUrl;
+    
+    @NotBlank(message = "取消重定向URL不能为空")
+    @Size(max = 255, message = "取消重定向URL长度不能超过255")
+    private String shopperCancelUrl;
+    
+    @NotBlank(message = "签名类型不能为空")
+    @Pattern(regexp = "^(MD5|SHA256)$", message = "签名类型必须为MD5或SHA256")
+    private String signType;
+    
+    @NotBlank(message = "签名不能为空")
+    @Size(max = 255, message = "签名长度不能超过255")
+    private String sign;
+    
+    @Size(max = 64, message = "商户用户ID长度不能超过64")
+    private String merchantUserId;
+    
+    @Size(min = 2, max = 4, message = "语言代码长度必须在2-4之间")
+    private String language = "en";
+    
+    @Pattern(regexp = "^(Y|N)$", message = "3DS参数必须为Y或N")
+    private String threeDSecure = "N";
+    
+    @Size(max = 64, message = "原始商户交易订单号长度不能超过64")
+    private String primaryMerchantTransactionId;
+    
+    private Integer periodsNum;
+    
+    @NotNull(message = "风控信息不能为空")
+    @Valid
+    private RiskInfoDTO riskInfo;
+    
+    @Size(max = 255, message = "异步通知地址长度不能超过255")
+    private String notificationUrl;
+    
+    @Size(max = 500, message = "备注长度不能超过500")
+    private String remark;
+}
+

mt-pay/src/main/java/com/mtkj/mtpay/dto/response/CheckoutResponseDTO.java

@@ -0,0 +1,37 @@
+package com.mtkj.mtpay.dto.response;
+
+import lombok.Data;
+
+import java.io.Serializable;
+
+/**
+ * Checkout接口响应DTO
+ */
+@Data
+public class CheckoutResponseDTO implements Serializable {
+    
+    private String clientId;
+    
+    private String accId;
+    
+    private String merchantTransactionId;
+    
+    private String code;
+    
+    private String description;
+    
+    private String token;
+    
+    private String paymentUrl;
+    
+    private String innerJsUrl;
+    
+    private String signType;
+    
+    private String sign;
+    
+    private String remark;
+    
+    private String paymentHtml;
+}
+

mt-pay/src/main/java/com/mtkj/mtpay/dto/risk/AirlineDTO.java

@@ -0,0 +1,15 @@
+package com.mtkj.mtpay.dto.risk;
+
+import lombok.Data;
+
+import java.io.Serializable;
+
+/**
+ * 航空信息DTO
+ */
+@Data
+public class AirlineDTO implements Serializable {
+    
+    // 根据实际需求添加字段
+}
+

mt-pay/src/main/java/com/mtkj/mtpay/dto/risk/BillingDTO.java

@@ -0,0 +1,31 @@
+package com.mtkj.mtpay.dto.risk;
+
+import lombok.Data;
+
+import java.io.Serializable;
+
+/**
+ * 账单地址DTO
+ */
+@Data
+public class BillingDTO implements Serializable {
+    
+    private String firstName;
+    
+    private String lastName;
+    
+    private String phone;
+    
+    private String email;
+    
+    private String street;
+    
+    private String postcode;
+    
+    private String city;
+    
+    private String state;
+    
+    private String country;
+}
+

mt-pay/src/main/java/com/mtkj/mtpay/dto/risk/CarRentalDTO.java

@@ -0,0 +1,15 @@
+package com.mtkj.mtpay.dto.risk;
+
+import lombok.Data;
+
+import java.io.Serializable;
+
+/**
+ * 租车信息DTO
+ */
+@Data
+public class CarRentalDTO implements Serializable {
+    
+    // 根据实际需求添加字段
+}
+