feat: 添加路由装饰器系统和全局异常处理

- 新增装饰器支持(@Get, @Post, @Put, @Delete, @Patch, @Controller)
- 实现路由自动注册机制(RouteScanner)
- 添加全局异常处理中间件(Exception)
- 实现统一响应体格式(ApiResponse)
- 新增请求体解析中间件(BodyParser)
- 重构控制器为类模式，支持装饰器路由
- 添加示例用户控制器(UserController)
- 更新TypeScript配置支持装饰器
- 添加reflect-metadata依赖
- 完善项目文档

Breaking Changes:
- 控制器现在返回数据而不是直接设置ctx.body
- 新增统一的API响应格式

pnpm-lock.yaml

@@ -23,6 +23,9 @@ importers:
       koa:
         specifier: ^3.0.1
         version: 3.0.1
+      reflect-metadata:
+        specifier: ^0.1.13
+        version: 0.1.14
     devDependencies:
       '@tsconfig/node-ts':
         specifier: ^23.6.1
@@ -1460,6 +1463,9 @@ packages:
   reduce-configs@1.1.1:
     resolution: {integrity: sha512-EYtsVGAQarE8daT54cnaY1PIknF2VB78ug6Zre2rs36EsJfC40EG6hmTU2A2P1ZuXnKAt2KI0fzOGHcX7wzdPw==}
 
+  reflect-metadata@0.1.14:
+    resolution: {integrity: sha512-ZhYeb6nRaXCfhnndflDK8qI6ZQ/YcWZCISRAWICW9XYqMUwjZM9Z0DveWX/ABN01oxSHwVxKQmxeYZSsm0jh5A==}
+
   resize-observer-polyfill@1.5.1:
     resolution: {integrity: sha512-LwZrotdHOo12nQuZlHEmtuXdqGoOD0OhaxopaNFxWzInpEgaLWoVuAMbTzixuosCx2nEG58ngzW3vxdWoxIgdg==}
 
@@ -2930,6 +2936,8 @@ snapshots:
 
   reduce-configs@1.1.1: {}
 
+  reflect-metadata@0.1.14: {}
+
   resize-observer-polyfill@1.5.1: {}
 
   resolve-from@4.0.0: {}