添加小游戏道具直购（present_goods）API支持

[Copilot]

用户反馈无法找到小游戏道具直购功能支持。根据微信官方文档，添加 present_goods API 实现。

新增内容

• API 接口：WxMaXPayService.presentGoods()
• 请求 Bean：WxMaXPayPresentGoodsRequest - 包含 openid、env、order_id、device_type、goods_id、goods_number
• 响应 Bean：WxMaXPayPresentGoodsResponse - 返回 order_id
• URL 常量：WxMaApiUrlConstants.XPay.PRESENT_GOODS_URL

使用示例

WxMaXPayPresentGoodsRequest request = WxMaXPayPresentGoodsRequest.builder()
    .openid("oUpF8uMuAJO_M2pxb1Q9zNjWeS6o")
    .env(0)
    .orderId("ORDER_20231219001")
    .deviceType(0)
    .goodsId("ITEM_001")
    .goodsNumber(1)
    .build();

WxMaXPayPresentGoodsResponse response = wxMaService.getXPayService()
    .presentGoods(request, sigParams);

实现模式与现有虚拟支付 API（如 presentCurrency）保持一致。

Original prompt

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This section details on the original issue you should resolve

<issue_title>请问小游戏的道具直购有支持吗？我没找到</issue_title>
<issue_description>这是道具直购的文档：
https://developers.weixin.qq.com/minigame/dev/guide/open-ability/virtual-payment/goods.html</issue_description>

Comments on the Issue (you are @copilot in this section)

Custom agent used: 全部用中文
需要用中文，包括PR标题和分析总结过程

• Fixes 请问小游戏的道具直购有支持吗？我没找到 #3810

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