feat(payment): 初始化支付模块核心代码

- 添加支付常量类PaymentConstants，定义支付状态、微信、支付宝、银联等相关常量
- 创建微信支付类型常量类WechatPayType，支持JSAPI、NATIVE、H5、APP支付方式
- 新增支付控制器PaymentController，提供创建支付、查询状态、退款等统一接口
- 实现支付回调控制器PaymentNotifyController，处理微信、支付宝、银联异步通知
- 添加支付请求数据传输对象PaymentRequest，支持多种支付方式参数校验
- 定义支付响应、状态更新请求等相关DTO类- 集成Swagger注解，完善接口文档说明- 添加参数校验和异常处理机制，确保支付流程安全可靠

java/payment/enums/PaymentChannel.java

@@ -0,0 +1,159 @@
+package com.gxwebsoft.payment.enums;
+
+/**
+ * 支付渠道枚举
+ * 定义具体的支付渠道类型
+ *
+ * @author 科技小王子
+ * @since 2025-01-26
+ */
+public enum PaymentChannel {
+    
+    /** 微信JSAPI支付 */
+    WECHAT_JSAPI("wechat_jsapi", "微信JSAPI支付", PaymentType.WECHAT),
+    
+    /** 微信Native支付 */
+    WECHAT_NATIVE("wechat_native", "微信Native支付", PaymentType.WECHAT_NATIVE),
+    
+    /** 微信H5支付 */
+    WECHAT_H5("wechat_h5", "微信H5支付", PaymentType.WECHAT),
+    
+    /** 微信APP支付 */
+    WECHAT_APP("wechat_app", "微信APP支付", PaymentType.WECHAT),
+    
+    /** 微信小程序支付 */
+    WECHAT_MINI("wechat_mini", "微信小程序支付", PaymentType.WECHAT),
+    
+    /** 支付宝网页支付 */
+    ALIPAY_WEB("alipay_web", "支付宝网页支付", PaymentType.ALIPAY),
+    
+    /** 支付宝手机网站支付 */
+    ALIPAY_WAP("alipay_wap", "支付宝手机网站支付", PaymentType.ALIPAY),
+    
+    /** 支付宝APP支付 */
+    ALIPAY_APP("alipay_app", "支付宝APP支付", PaymentType.ALIPAY),
+    
+    /** 支付宝小程序支付 */
+    ALIPAY_MINI("alipay_mini", "支付宝小程序支付", PaymentType.ALIPAY),
+    
+    /** 银联网关支付 */
+    UNION_WEB("union_web", "银联网关支付", PaymentType.UNION_PAY),
+    
+    /** 银联手机支付 */
+    UNION_WAP("union_wap", "银联手机支付", PaymentType.UNION_PAY),
+    
+    /** 余额支付 */
+    BALANCE("balance", "余额支付", PaymentType.BALANCE),
+    
+    /** 现金支付 */
+    CASH("cash", "现金支付", PaymentType.CASH),
+    
+    /** POS机支付 */
+    POS("pos", "POS机支付", PaymentType.POS);
+
+    private final String code;
+    private final String name;
+    private final PaymentType paymentType;
+
+    PaymentChannel(String code, String name, PaymentType paymentType) {
+        this.code = code;
+        this.name = name;
+        this.paymentType = paymentType;
+    }
+
+    public String getCode() {
+        return code;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public PaymentType getPaymentType() {
+        return paymentType;
+    }
+
+    /**
+     * 根据代码获取支付渠道
+     */
+    public static PaymentChannel getByCode(String code) {
+        if (code == null) {
+            return null;
+        }
+        for (PaymentChannel channel : values()) {
+            if (channel.code.equals(code)) {
+                return channel;
+            }
+        }
+        return null;
+    }
+
+    /**
+     * 根据支付类型获取默认渠道
+     */
+    public static PaymentChannel getDefaultByPaymentType(PaymentType paymentType) {
+        if (paymentType == null) {
+            return null;
+        }
+        
+        switch (paymentType) {
+            case WECHAT:
+                return WECHAT_JSAPI;
+            case WECHAT_NATIVE:
+                return WECHAT_NATIVE;
+            case ALIPAY:
+                return ALIPAY_WEB;
+            case UNION_PAY:
+                return UNION_WEB;
+            case BALANCE:
+                return BALANCE;
+            case CASH:
+                return CASH;
+            case POS:
+                return POS;
+            default:
+                return null;
+        }
+    }
+
+    /**
+     * 是否为微信支付渠道
+     */
+    public boolean isWechatChannel() {
+        return paymentType.isWechatPay();
+    }
+
+    /**
+     * 是否为支付宝支付渠道
+     */
+    public boolean isAlipayChannel() {
+        return paymentType == PaymentType.ALIPAY;
+    }
+
+    /**
+     * 是否为银联支付渠道
+     */
+    public boolean isUnionPayChannel() {
+        return paymentType == PaymentType.UNION_PAY;
+    }
+
+    /**
+     * 是否为第三方支付渠道
+     */
+    public boolean isThirdPartyChannel() {
+        return paymentType.isThirdPartyPay();
+    }
+
+    /**
+     * 是否支持退款
+     */
+    public boolean supportRefund() {
+        return isThirdPartyChannel();
+    }
+
+    @Override
+    public String toString() {
+        return String.format("PaymentChannel{code='%s', name='%s', paymentType=%s}", 
+            code, name, paymentType);
+    }
+}