build: 初始化构建后端并集成Gin框架，开放健康检查端口

backend/internal/model/response.go

@@ -0,0 +1,15 @@
+package model
+
+type Response struct {
+	Code    int    `json:"code"`
+	Message string `json:"message"`
+	Data    any    `json:"data,omitempty"`
+}
+
+func OK(data any) Response {
+	return Response{Code: 0, Message: "ok", Data: data}
+}
+
+func Fail(code int, msg string) Response {
+	return Response{Code: code, Message: msg}
+}