perf: 优化旧版浏览器页面恢复与资源加载

- 页面恢复时延后版本检查并补齐根背景，减少白闪与首帧卡顿

- 面向 Chrome 90 收敛公共分包，按需加载资源弹窗和知识库面板

- 压缩工作流图标并补充延迟加载与可见性生命周期测试

easyflow-ui-usercenter/packages/@core/base/design/src/css/global.css

@@ -33,6 +33,8 @@
   html {
     @apply size-full;
 
+    background-color: hsl(var(--background));
+
     /* scrollbar-gutter: stable; */
   }
 

easyflow-ui-usercenter/packages/effects/layouts/src/widgets/check-updates/check-updates.test.ts

@@ -0,0 +1,76 @@
+import { flushPromises, mount } from '@vue/test-utils';
+
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+
+import CheckUpdates from './check-updates.vue';
+
+const { modalOpen } = vi.hoisted(() => ({
+  modalOpen: vi.fn(),
+}));
+
+vi.mock('@easyflow/locales', () => ({
+  $t: (key: string) => key,
+}));
+
+vi.mock('@easyflow-core/popup-ui', () => ({
+  useEasyFlowModal: () => [
+    {
+      name: 'UpdateNoticeModalStub',
+      template: '<div><slot /></div>',
+    },
+    { open: modalOpen },
+  ],
+}));
+
+describe('check updates visibility lifecycle', () => {
+  let hidden = false;
+
+  beforeEach(() => {
+    hidden = false;
+    modalOpen.mockClear();
+    vi.useFakeTimers();
+    vi.spyOn(document, 'hidden', 'get').mockImplementation(() => hidden);
+    vi.stubGlobal('location', { hostname: 'customer.example' });
+    vi.stubGlobal(
+      'fetch',
+      vi.fn().mockResolvedValue({
+        headers: {
+          get: (name: string) => (name === 'etag' ? 'version-1' : null),
+        },
+      }),
+    );
+  });
+
+  afterEach(() => {
+    vi.useRealTimers();
+    vi.restoreAllMocks();
+    vi.unstubAllGlobals();
+  });
+
+  it('restarts polling without fetching immediately when the page becomes visible', async () => {
+    const wrapper = mount(CheckUpdates);
+    const fetchMock = vi.mocked(fetch);
+
+    hidden = true;
+    document.dispatchEvent(new Event('visibilitychange'));
+    hidden = false;
+    document.dispatchEvent(new Event('visibilitychange'));
+
+    expect(fetchMock).not.toHaveBeenCalled();
+
+    await vi.advanceTimersByTimeAsync(59_999);
+    expect(fetchMock).not.toHaveBeenCalled();
+
+    await vi.advanceTimersByTimeAsync(1);
+    await flushPromises();
+
+    expect(fetchMock).toHaveBeenCalledTimes(1);
+    expect(fetchMock).toHaveBeenCalledWith(
+      '/',
+      expect.objectContaining({ method: 'HEAD' }),
+    );
+    expect(modalOpen).not.toHaveBeenCalled();
+
+    wrapper.unmount();
+  });
+});

easyflow-ui-usercenter/packages/effects/layouts/src/widgets/check-updates/check-updates.vue

@@ -124,11 +124,8 @@ function handleVisibilitychange() {
   if (document.hidden) {
     stop();
   } else {
-    runUpdateCheck().finally(() => {
-      if (!document.hidden) {
-        start();
-      }
-    });
+    // 恢复窗口时只重启轮询，避免与旧浏览器的首帧重绘争抢资源。
+    start();
   }
 }