feat(chat): prompt facebook users to open external browser

src/data/storage/auth/auth_storage.ts

@@ -3,8 +3,6 @@
 /**
  * AuthStorage 完整实现（基于 unstorage 抽象）
  *
- * 原始 Dart: lib/data/services/storage/auth_storage.dart
- *
  * SECURITY: 当前与 Dart 端行为一致，refresh_token 以明文存于 localStorage。
  * 后续轮次将升级到 HttpOnly Cookie 方案，参见 `clearAuthData` 处的 TODO 标记。
  *
@@ -99,6 +97,9 @@ export class AuthStorage implements IAuthStorage {
   setFacebookId(id: string): Promise<ResultT<void>> {
     return SpAsyncUtil.setString(StorageKeys.facebookId, id);
   }
+  clearFacebookId(): Promise<ResultT<void>> {
+    return SpAsyncUtil.remove(StorageKeys.facebookId);
+  }
 
   // ---- bulk clear ----
 
@@ -107,6 +108,8 @@ export class AuthStorage implements IAuthStorage {
     if (!r1.success) return r1;
     const r2 = await this.clearGuestToken();
     if (!r2.success) return r2;
-    return this.clearRefreshToken();
+    const r3 = await this.clearRefreshToken();
+    if (!r3.success) return r3;
+    return this.clearFacebookId();
   }
 }

src/data/storage/auth/iauth_storage.ts

@@ -31,6 +31,7 @@ export interface IAuthStorage {
 
   getFacebookId(): Promise<Result<string | null>>;
   setFacebookId(id: string): Promise<Result<void>>;
+  clearFacebookId(): Promise<Result<void>>;
 
   clearAuthData(): Promise<Result<void>>;
 }