fix: 修复 AI 设计会话失效后的伪登录

问题：Main 刷新令牌返回 401 后已清空会话，但 Renderer 仍保留用户信息，AI 设计持续返回 AUTH_REQUIRED。

实现：认证初始化等待 Main 同步完成；同步或刷新失败清理登录态；Workspace 识别结构化认证错误并在重新登录后恢复加载；路由守卫响应登录状态变化。

验证：49 个聚焦测试通过，TypeScript、聚焦 Lint 与 Vite 生产构建通过。

tests/unit/login-page.test.tsx

@@ -1,4 +1,4 @@
-import { fireEvent, render, screen, waitFor } from '@testing-library/react';
+import { act, fireEvent, render, screen, waitFor } from '@testing-library/react';
 import { beforeEach, describe, expect, it, vi } from 'vitest';
 import { MemoryRouter, Route, Routes } from 'react-router-dom';
 import { Login } from '@/pages/Login';
@@ -66,6 +66,52 @@ describe('Login page', () => {
     expect(await screen.findByRole('button', { name: 'Continue in browser' })).toBeInTheDocument();
   });
 
+  it('redirects an open protected route when the current auth session is invalidated', async () => {
+    useSettingsStore.setState({ setupComplete: true });
+    useAuthStore.setState({
+      initialized: true,
+      loading: false,
+      error: null,
+      authBase: 'https://biz.nianxx.cn/auth/',
+      clientId: 'app',
+      accessToken: 'access-token',
+      refreshToken: 'refresh-token',
+      tokenType: 'Bearer',
+      expiresAt: Date.now() + 60_000,
+      user: {
+        username: 'brother7',
+        userId: '1',
+        tenantId: null,
+        deptId: null,
+        authorities: [],
+      },
+    });
+    hostApiFetchMock.mockResolvedValue({ success: true });
+
+    render(
+      <MemoryRouter initialEntries={['/makelore-home']}>
+        <App />
+      </MemoryRouter>,
+    );
+
+    await waitFor(() => expect(hostApiFetchMock).toHaveBeenCalledWith(
+      '/api/auth/session/sync',
+      expect.any(Object),
+    ));
+
+    act(() => {
+      useAuthStore.setState({
+        accessToken: null,
+        refreshToken: null,
+        tokenType: null,
+        expiresAt: null,
+        user: null,
+      });
+    });
+
+    expect(await screen.findByRole('button', { name: 'Continue in browser' })).toBeInTheDocument();
+  });
+
   it('opens only the local image workspace anonymously when the explicit development mode is active', async () => {
     useSettingsStore.setState({ setupComplete: true });
     window.electron.imageWorkspaceLocalDevelopment = true;