docs(developer-guide): 新增开发指南分类（架构/需求/详细设计/数据模型/贡献指南） - #6

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v3, actions/setup-node@v3, borales/actions-yarn@v4. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/