feat(auth): persist login provider for restored sessions

src/data/storage/auth/auth_storage.ts

@@ -11,9 +11,10 @@
  *   - 浏览器 → `localStorage` driver；SSR → memory driver（unstorage 自动）
  *   - 单例挂在 class 静态字段，规避 HMR 复用污染
  *   - `hasXxx` = `token != null && token.length > 0`，对齐 Dart 端 `isNotEmpty` 语义
- *   - `clearAuthData` 顺序清理：loginToken → guestToken → refreshToken，任一失败立即返回
+ *   - `clearAuthData` 顺序清理：loginToken → loginProvider → guestToken → refreshToken，任一失败立即返回
  */
 
+import { LoginStatus, type LoginStatus as LoginStatusT } from "@/data/dto/auth";
 import { Result, type Result as ResultT, SpAsyncUtil } from "@/utils";
 import { StorageKeys } from "../storage_keys";
 import type { IAuthStorage } from "./iauth_storage";
@@ -48,6 +49,22 @@ export class AuthStorage implements IAuthStorage {
     return SpAsyncUtil.remove(StorageKeys.loginToken);
   }
 
+  // ---- login provider ----
+
+  async getLoginProvider(): Promise<ResultT<LoginStatusT | null>> {
+    const r = await SpAsyncUtil.getString(StorageKeys.loginProvider);
+    if (!r.success) return Result.err(r.error);
+    if (r.data === null || r.data.length === 0) return Result.ok(null);
+    if (isLoginStatus(r.data)) return Result.ok(r.data);
+    return Result.ok(null);
+  }
+  setLoginProvider(provider: LoginStatusT): Promise<ResultT<void>> {
+    return SpAsyncUtil.setString(StorageKeys.loginProvider, provider);
+  }
+  clearLoginProvider(): Promise<ResultT<void>> {
+    return SpAsyncUtil.remove(StorageKeys.loginProvider);
+  }
+
   // ---- guest token ----
 
   getGuestToken(): Promise<ResultT<string | null>> {
@@ -103,10 +120,16 @@ export class AuthStorage implements IAuthStorage {
   async clearAuthData(): Promise<ResultT<void>> {
     const r1 = await this.clearLoginToken();
     if (!r1.success) return r1;
-    const r2 = await this.clearGuestToken();
+    const r2 = await this.clearLoginProvider();
     if (!r2.success) return r2;
-    const r3 = await this.clearRefreshToken();
+    const r3 = await this.clearGuestToken();
     if (!r3.success) return r3;
+    const r4 = await this.clearRefreshToken();
+    if (!r4.success) return r4;
     return this.clearFacebookId();
   }
 }
+
+function isLoginStatus(value: string): value is LoginStatusT {
+  return Object.values(LoginStatus).includes(value as LoginStatusT);
+}