fix: update mock dev server api handling

[shiqiWang0]

Description

修复本地开发环境中 mock API 的匹配与代理配置问题。

Changes

• 将 mockDevServerPlugin 的 mock 文件匹配路径从 app/mock/**/*.mock.* 调整为 mock/**/*.mock.*
• 为 mock 插件增加 /api 请求前缀匹配
• 移除 Vite dev server 中空 target 的 /api proxy 配置

How Has This Been Tested?

• 启动本地开发服务
• 验证 /api 前缀请求可以被 mock dev server 正常处理

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules