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/testing/chi/main.go

@@ -0,0 +1,17 @@
+package main
+
+import (
+    "net/http"
+
+    "github.com/go-chi/chi/v5"
+    "github.com/go-chi/chi/v5/middleware"
+)
+
+func main() {
+    r := chi.NewRouter()
+    r.Use(middleware.Logger)
+    r.Get("/", func(w http.ResponseWriter, r *http.Request) {
+        w.Write([]byte("Hello World!"))
+    })
+    http.ListenAndServe(":30000", r)
+}