docs: UI-02 acceptance record and visual verification

Co-Authored-By: Claude Code <noreply@anthropic.com>

apps/viewer/src/__tests__/lightbox.spec.ts

@@ -432,6 +432,32 @@ describe('photo lightbox dark viewer (UI-02 V04)', () => {
     trigger.remove();
   });
 
+  // UI-02 Task 6 无障碍抽检（§5.3）：Tab 循环困于对话框——两端折回，不穿透。
+  it('traps Tab focus inside the dialog (wrap-around at both ends)', async () => {
+    const wrapper = mountLightbox('p2');
+    document.body.appendChild(wrapper.element);
+    await flushPromises();
+
+    const focusables = Array.from(
+      wrapper.element.querySelectorAll('button:not([disabled])'),
+    ).filter((el): el is HTMLElement => el instanceof HTMLElement);
+    expect(focusables.length).toBeGreaterThan(1);
+    const first = focusables[0]!;
+    const last = focusables[focusables.length - 1]!;
+
+    // 末元素正向 Tab → 折回首元素。
+    last.focus();
+    last.dispatchEvent(new KeyboardEvent('keydown', { key: 'Tab', bubbles: true, cancelable: true }));
+    expect(document.activeElement).toBe(first);
+
+    // 首元素 Shift+Tab → 折回末元素。
+    first.focus();
+    first.dispatchEvent(
+      new KeyboardEvent('keydown', { key: 'Tab', shiftKey: true, bubbles: true, cancelable: true }),
+    );
+    expect(document.activeElement).toBe(last);
+  });
+
   it('locks body scroll while open and restores the previous value on close', async () => {
     document.body.style.overflow = 'auto';
     const wrapper = mountLightbox('p2');
@@ -454,6 +480,16 @@ describe('photo lightbox dark viewer (UI-02 V04)', () => {
     expect(source).toContain('env(safe-area-inset-top, 0px)');
     expect(source).toContain('env(safe-area-inset-bottom, 0px)');
   });
+
+  it('layers the fullscreen overlay above the sticky topbar (close button clickable)', () => {
+    // jsdom 无布局：源级断言（同上）。覆盖层 z=200 须高于 sticky 顶栏 z=120
+    // （App.vue）——否则顶栏盖住关闭按钮的可点区（e2e 曾拦截 click 的真实回归）。
+    const source = readFileSync(
+      join(dirname(fileURLToPath(import.meta.url)), '..', 'components', 'PhotoLightbox.vue'),
+      'utf8',
+    );
+    expect(source).toMatch(/\.photo-viewer\s*\{[^}]*z-index:\s*200/s);
+  });
 });
 
 describe('photo lightbox interactions (UI-02 V05)', () => {