收口统一弹窗关闭按钮

新增 PlatformModalCloseButton pixel 变体承接像素风关闭入口

将 UnifiedModal 头部关闭按钮迁移到 PlatformModalCloseButton

补充平台态和像素态关闭按钮测试

更新 PlatformUiKit 文档和 Hermes 决策记录

src/components/common/PlatformModalCloseButton.test.tsx

@@ -71,9 +71,20 @@ test('supports platform icon close button', () => {
   const button = screen.getByRole('button', { name: '关闭素材图片' });
 
   expect(button.className).toContain('platform-icon-button');
+  expect(button.className).toContain('disabled:opacity-45');
   expect(button.querySelector('svg')).toBeTruthy();
 });
 
+test('supports pixel close button', () => {
+  render(<PlatformModalCloseButton label="关闭像素弹窗" variant="pixel" />);
+
+  const button = screen.getByRole('button', { name: '关闭像素弹窗' });
+
+  expect(button.className).toContain('bg-black/20');
+  expect(button.className).toContain('text-zinc-400');
+  expect(button.className).toContain('disabled:opacity-45');
+});
+
 test('supports editor dark close button', () => {
   render(
     <PlatformModalCloseButton label="关闭角色自定义" variant="editorDark" />,