feat: 添加 chi 练习与 Gitea CI 实践

- 新增 chi 路由示例并更新依赖
- 用简单 CI 实践笔记替换 Polaris 部署笔记
- 添加本地 Gitea 与 runner 配置示例，注册令牌从环境变量读取

go/practice/go.sum

@@ -17,6 +17,8 @@ github.com/gin-contrib/sse v1.1.1 h1:uGYpNwTacv5R68bSGMapo62iLTRa9l5zxGCps4hK6ko
 github.com/gin-contrib/sse v1.1.1/go.mod h1:QXzuVkA0YO7o/gun03UI1Q+FTI8ZV/n5t03kIQAI89s=
 github.com/gin-gonic/gin v1.12.0 h1:b3YAbrZtnf8N//yjKeU2+MQsh2mY5htkZidOM7O0wG8=
 github.com/gin-gonic/gin v1.12.0/go.mod h1:VxccKfsSllpKshkBWgVgRniFFAzFb9csfngsqANjnLc=
+github.com/go-chi/chi/v5 v5.5.0 h1:xdKQ1dJmVJsmgahrXSKhUx8NyVPzpwdlyrrQFpMPJgg=
+github.com/go-chi/chi/v5 v5.5.0/go.mod h1:d1IG7GtKPSjPyBP365PH8sAGVHk3qfB/IhjFNRH1wWM=
 github.com/go-playground/assert/v2 v2.2.0 h1:JvknZsQTYeFEAhQwI4qEt9cyV5ONwRHC+lYKSsYSR8s=
 github.com/go-playground/assert/v2 v2.2.0/go.mod h1:VDjEfimB/XKnb+ZQfWdccd7VUvScMdVu0Titje2rxJ4=
 github.com/go-playground/locales v0.14.1 h1:EWaQ/wswjilfKLTECiXz7Rh+3BjFhfDFKv/oXslEjJA=