借助 AI Loop 统一后端请求与响应格式

const { msg } = await updateUserPassword();
if (msg === 'ok') {
}

const res = await updateUserPassword();
if (res.ok) {
}

## 使用方式

### 基础成功响应

```go
func GetUser(c *gin.Context) {
  var user User
  // ... 获取用户
  response.Success(c, user)

}

// 响应示例: {"success": true, "msg": "ok", "data": {...}}

### 使用泛型的成功响应

```go
response.Success(c, MyStruct{Field: "value"})
// 响应示例: {"success": true, "msg": "ok", "data": {"field": "value"}}

### 带分页的成功响应

```go
var users []User
meta := &response.PaginationMeta{
  Page:       1,
  PerPage:    10,
  TotalCount: 100,
}
// ... 获取用户列表

response.SuccessWithMeta(c, users, meta)
// 响应示例: {"success": true, "msg": "ok", "data": [...], "meta": {"page": 1, "per_page": 10, "total_count": 100}}

### 错误响应

```go
response.Error(c, http.StatusBadRequest, http.StatusBadRequest, "missing id")
// 响应示例: {"success": false, "error": {"code": 400, "message": "missing id"}}

response.BadRequest(c, "INVALID_PARAM", "missing id")
response.NotFound(c, "user not found")
response.Unauthorized(c, "token expired")
response.InternalError(c, "database error")

## 辅助函数

| Function | Status Code | Default Code | Description |
|----------|-------------|--------------|--------------|
| `Success(c, data)` | 200 | - | 带数据的成功响应 |
| `SuccessWithMeta(c, data, meta)` | 200 | - | 带分页信息的成功响应 |
| `Error(c, status, code, msg)` | custom | custom | 自定义错误响应 |
| `BadRequest(c, code, msg)` | 400 | code | 错误请求 |
| `Unauthorized(c, msg)` | 401 | UNAUTHORIZED | 未授权 |
| `Forbidden(c, msg)` | 403 | FORBIDDEN | 禁止访问 |
| `NotFound(c, msg)` | 404 | NOT_FOUND | 资源不存在 |
| `InternalError(c, msg)` | 500 | INTERNAL_ERROR | 内部服务器错误 |

## 优势

1. **类型安全**：泛型保留响应数据的类型，而不是使用 interface{}
2. **一致性**：所有接口使用统一的响应 Envelope 格式
3. **开发体验**：清晰的成功（msg: "ok"）与错误结构
4. **分页支持**：内建分页 metadata

/goal 将 internal/handler/ 下所有 HTTP Handler 迁移为使用 .agents/skills/response-helper/SKILL.md 中定义的 response helper

Outcome:
internal/handler/ 中的每个 handler 必须仅通过 response helper 返回响应。任何 handler 不得直接调用 c.JSON、c.String 或任何原始响应方法。

Verification surface:
1. Run `grep -rn "c\.JSON\|c\.String\|c\.Data" internal/handler/` — result must be empty.
2. Run `go build ./...` — must exit 0.
3. Run `go test ./internal/handler/...` — must exit 0 with no failures.

Constraints:
- Do not change any business logic, only the response layer.
- Do not modify files outside internal/handler/ and internal/helper/.
- Do not introduce new dependencies.
- HTTP status codes must follow the standard defined in SKILL.md (2xx success, 4xx client error, 5xx server error). Do not preserve any custom msg or status field from the old implementation.

Boundaries:
- Read .agents/skills/response-helper/SKILL.md before making any changes.
- Work only on files under internal/handler/.
- You may create or modify internal/helper/response.go if the helper does not yet exist.

Iteration:
After each handler file is migrated, run the verification commands before moving to the next file. If any check fails, fix it before continuing. Do not batch multiple files into one turn.