feat(channel): 新增视频号小店商家客服 API（cosupload/sendmsg）

[Copilot]

当前 weixin-java-channel 缺少商家客服能力，无法覆盖微信小店官方文档中的两项基础接口：上传多媒体资源与发送客服消息。该变更补齐服务入口、请求/响应模型与 API 常量，实现对 cosupload 与 sendmsg 的标准化调用。

• 变更概览

  • 新增商家客服服务接口 WxChannelKfService 与实现 WxChannelKfServiceImpl
  • 在 WxChannelService / BaseWxChannelServiceImpl 中接入 getKfService()，保持与现有子服务一致的使用方式
  • 新增商家客服 API 常量：
    • https://api.weixin.qq.com/channels/ec/commkf/cosupload
    • https://api.weixin.qq.com/channels/ec/commkf/sendmsg

• 请求与响应模型

  • 新增上传响应模型：WxChannelKfCosUploadResponse（cos_url）
  • 新增发送消息请求模型：WxChannelKfSendMsgParam
    • 支持官方定义消息体：text / image / video / file / product_share / order_share
    • 映射官方字段：request_id、open_id、msg_type
  • 新增发送消息响应模型：WxChannelKfSendMsgResponse（msg_id）

• 接口设计要点

  • 上传接口提供字节数组重载，内部统一走 multipart 上传，并附带 open_id、msg_type 表单字段
  • 发送接口直接接收结构化参数对象，避免 Object content 的弱类型与字段漂移风险

WxChannelKfService kfService = wxChannelService.getKfService();

String cosUrl = kfService.uploadMedia(openId, "image", "img.jpg", imageBytes);

WxChannelKfSendMsgParam param = new WxChannelKfSendMsgParam();
param.setOpenId(openId);
param.setMsgType("image");
param.setImage(new WxChannelKfSendMsgParam.CosUrlMessage(cosUrl));

WxChannelKfSendMsgResponse resp = kfService.sendMessage(param);
String msgId = resp.getMsgId();

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Use the documented KF endpoints

When clients call either new KF method, these constants send the request to /channels/ec/commkf/..., but the WeChat store KF APIs are exposed under /channels/ec/kf/cosupload and /channels/ec/kf/sendmsg. As written, both upload and send-message calls are routed to the wrong API path and will fail before the new request/response models can be used.

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[Copilot]

Pull request overview

该 PR 为 weixin-java-channel 新增视频号小店商家客服能力，补齐多媒体上传与客服消息发送两个基础 API 的服务入口、模型与常量。

Changes:

• 新增商家客服服务接口及实现，并接入 WxChannelService#getKfService()。
• 新增 cosupload / sendmsg API 常量及对应请求、响应模型。
• 新增 Bean 序列化与反序列化测试，覆盖客服消息参数和响应字段映射。

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
weixin-java-channel/src/main/java/me/chanjar/weixin/channel/constant/WxChannelApiUrlConstants.java	新增商家客服相关 API 地址常量。
weixin-java-channel/src/main/java/me/chanjar/weixin/channel/api/WxChannelService.java	暴露商家客服子服务入口。
weixin-java-channel/src/main/java/me/chanjar/weixin/channel/api/WxChannelKfService.java	定义上传媒体与发送客服消息接口。
weixin-java-channel/src/main/java/me/chanjar/weixin/channel/api/impl/BaseWxChannelServiceImpl.java	懒加载并返回客服服务实现。
weixin-java-channel/src/main/java/me/chanjar/weixin/channel/api/impl/WxChannelKfServiceImpl.java	实现 multipart 上传与消息发送调用。
weixin-java-channel/src/main/java/me/chanjar/weixin/channel/bean/kf/WxChannelKfSendMsgParam.java	新增发送客服消息请求模型。
weixin-java-channel/src/main/java/me/chanjar/weixin/channel/bean/kf/WxChannelKfCosUploadResponse.java	新增上传响应模型。
weixin-java-channel/src/main/java/me/chanjar/weixin/channel/bean/kf/WxChannelKfSendMsgResponse.java	新增发送消息响应模型。
weixin-java-channel/src/test/java/me/chanjar/weixin/channel/bean/kf/WxChannelKfBeanTest.java	新增客服相关 Bean JSON 映射测试。