feat: add frontend development guidelines and structure documentation

- Introduced API guidelines for interface contracts and request handling.
- Added design tokens usage guidelines for consistent styling across the project.
- Established DTO guidelines for defining request parameters and response data types.
- Created frontend structure guidelines to clarify directory organization and code placement rules.
- Compiled a comprehensive frontend development guideline document covering various aspects of the development process.
- Implemented quality guidelines to ensure code maintainability and adherence to best practices.

AI Coding/projects/index.md

@@ -0,0 +1,11 @@
+# Projects
+
+为每个项目维护一份简短索引，记录：
+
+- 仓库位置
+- 项目内知识入口
+- 已贡献到公共仓库的经验
+- 从公共仓库同步回项目的规则或资产
+- 最后审计日期
+
+项目专属事实和强制规则仍以项目仓库为准。