feat(assets): add chat typing indicator lottie animation

src/data/storage/user/user_storage.ts

@@ -0,0 +1,93 @@
+"use client";
+
+/**
+ * UserStorage 完整实现（KV / localStorage）
+ *
+ * 对齐 Dart 端 `UserStorage`（lib/data/services/storage/user_storage.dart）：
+ *   - 三个独立字段：User 对象 / userId / avatarUrl
+ *   - `clearUserData()` 批量清空
+ *
+ * 设计沿用 AuthStorage 模式：组合 `LocalStorage`（非继承）+ 单例 + Zod 校验。
+ *
+ * 边界：
+ *   - `getUser` 走 `UserSchema` 解析：缺字段时 Zod `.default()` 自动兜底
+ *   - `setUser` 走 `UserSchema` 校验写入：保证存储的总是完整 UserData
+ *   - 单例挂在 class 静态字段，HMR 复用安全
+ */
+
+import { UserSchema, type UserData } from "@/data/models";
+import { LocalStorage } from "../local_storage";
+import { type Result as ResultT } from "../result";
+import { StorageKeys } from "../storage_keys";
+import type { IUserStorage } from "./iuser_storage";
+
+export class UserStorage implements IUserStorage {
+  private readonly ls: LocalStorage;
+  private static _instance: UserStorage | null = null;
+
+  constructor(localStorage?: LocalStorage) {
+    this.ls = localStorage ?? LocalStorage.getInstance();
+  }
+
+  static getInstance(): UserStorage {
+    if (!UserStorage._instance) UserStorage._instance = new UserStorage();
+    return UserStorage._instance;
+  }
+
+  /** @internal */
+  static _resetForTests(): void {
+    UserStorage._instance = null;
+  }
+
+  // ---- user object ----
+
+  getUser(): Promise<ResultT<UserData | null>> {
+    return this.ls.getJson(StorageKeys.user, UserSchema);
+  }
+
+  setUser(user: UserData): Promise<ResultT<void>> {
+    return this.ls.setJson(StorageKeys.user, user, UserSchema);
+  }
+
+  clearUser(): Promise<ResultT<void>> {
+    return this.ls.remove(StorageKeys.user);
+  }
+
+  // ---- userId ----
+
+  getUserId(): Promise<ResultT<string | null>> {
+    return this.ls.getString(StorageKeys.userId);
+  }
+
+  setUserId(id: string): Promise<ResultT<void>> {
+    return this.ls.setString(StorageKeys.userId, id);
+  }
+
+  clearUserId(): Promise<ResultT<void>> {
+    return this.ls.remove(StorageKeys.userId);
+  }
+
+  // ---- avatarUrl ----
+
+  getAvatarUrl(): Promise<ResultT<string | null>> {
+    return this.ls.getString(StorageKeys.userAvatar);
+  }
+
+  setAvatarUrl(url: string): Promise<ResultT<void>> {
+    return this.ls.setString(StorageKeys.userAvatar, url);
+  }
+
+  clearAvatarUrl(): Promise<ResultT<void>> {
+    return this.ls.remove(StorageKeys.userAvatar);
+  }
+
+  // ---- bulk clear ----
+
+  async clearUserData(): Promise<ResultT<void>> {
+    const r1 = await this.clearUser();
+    if (r1.kind === "failure") return r1;
+    const r2 = await this.clearUserId();
+    if (r2.kind === "failure") return r2;
+    return this.clearAvatarUrl();
+  }
+}