refactor(user): split user-machine into helpers and actors

Mirror the existing chat-module structure (chat-machine.helpers.ts +
chat-machine.actors.ts) for consistency across state-machine modules.

Split:
- user-machine.helpers.ts: pure data layer (no XState dep)
  - userStorage singleton
  - InitData interface
  - toView DTO → UserView mapper
  - readInitData (parallel getUser + getAvatarUrl)
- user-machine.actors.ts: async actor implementations (fromPromise)
  - userRepo / authRepo injection
  - userInitActor / userFetchActor / userLogoutActor
- user-machine.ts: only setup().createMachine() — keeps inline assign
  actions referencing context/event where they belong, imports actors
  (not helpers, per the layered convention).

No behaviour change — only file boundaries moved. Public API (exports of
UserState / UserEvent / initialState / userMachine / UserMachine) stays
identical so external imports are untouched.

src/stores/user/user-machine.actors.ts

@@ -0,0 +1,74 @@
+/**
+ * User 状态机：Actors（异步服务）
+ *
+ * 从 `user-machine.ts` 抽出的"Actors"段：
+ *   - `userInitActor`（fromPromise：读 UserStorage 并行 user + avatarUrl）
+ *   - `userFetchActor`（fromPromise：调 API + 持久化到本地）
+ *   - `userLogoutActor`（fromPromise：auth logout + 清本地数据）
+ *
+ * 设计：
+ *   - 依赖 `user-machine.helpers.ts`（toView, readInitData, userStorage）
+ *   - 仓库以接口类型注入（调用面只看接口，运行时仍是同一单例）
+ *   - 命名约定：`[user-machine]` 前缀日志（如未来加）—— 与 chat 模块对齐
+ */
+
+import { fromPromise } from "xstate";
+
+import type { UserView } from "@/models/user/user";
+import { userRepository } from "@/data/repositories/user_repository";
+import { authRepository } from "@/data/repositories/auth_repository";
+import type {
+  IAuthRepository,
+  IUserRepository,
+} from "@/data/repositories/interfaces";
+import { Result } from "@/utils/result";
+
+import { type InitData, readInitData, toView, userStorage } from "./user-machine.helpers";
+
+// ============================================================
+// 仓库注入
+// ============================================================
+// 仓库以接口类型注入：调用面只看接口，运行时仍是同一单例
+const userRepo: IUserRepository = userRepository;
+const authRepo: IAuthRepository = authRepository;
+
+// ============================================================
+// Init actor：从 UserStorage 读 user + avatarUrl
+// ============================================================
+/**
+ * 读本地 user + avatarUrl（并行）。
+ * - 失败/无数据 → 返回 null，不抛错（machine 走 onDone 回到 idle，context 是 null）
+ * - onDone 赋 currentUser + avatarUrl 到 context
+ */
+export const userInitActor = fromPromise<InitData>(async () => readInitData());
+
+// ============================================================
+// Fetch actor：调 API 拉当前用户 + 持久化
+// ============================================================
+/**
+ * 调 `userRepo.getCurrentUser` 拉当前 user：
+ * - 成功 → 转 UserView + 写本地（userStorage.setUser）→ 返回 View
+ * - 失败 → 返回 null（machine 走 onDone，context 保持不变；onError 兜底）
+ */
+export const userFetchActor = fromPromise<UserView | null>(async () => {
+  const result = await userRepo.getCurrentUser();
+  if (Result.isErr(result)) return null;
+  const view = toView(result.data.toJson());
+  // 持久化到本地
+  await userStorage.setUser(result.data.toJson());
+  return view;
+});
+
+// ============================================================
+// Logout actor：后端登出 + 清本地用户数据
+// ============================================================
+/**
+ * 登出：
+ * - 调 `authRepo.logout` 让后端吊销 token
+ * - `userStorage.clearUserData` 清本地 user / avatar 等
+ * - onDone / onError 都跑 `clearUser` action（machine 层）—— 失败也清本地
+ */
+export const userLogoutActor = fromPromise<void>(async () => {
+  await authRepo.logout();
+  await userStorage.clearUserData();
+});