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/UnifiedModal.tsx

@@ -1,4 +1,3 @@
-import { X } from 'lucide-react';
 import {
   type CSSProperties,
   type ReactNode,
@@ -8,6 +7,7 @@ import {
 import { createPortal } from 'react-dom';
 
 import { getNineSliceStyle, UI_CHROME } from '../../uiAssets';
+import { PlatformModalCloseButton } from './PlatformModalCloseButton';
 
 type UnifiedModalVariant = 'platform' | 'pixel';
 type UnifiedModalSize = 'sm' | 'md' | 'lg' | 'xl' | 'fullscreen';
@@ -145,10 +145,6 @@ function UnifiedModalContent({
     ? 'flex flex-wrap items-center justify-end gap-3 border-t border-white/10 px-4 py-3 sm:px-5 sm:py-4'
     : 'flex flex-wrap items-center justify-end gap-3 border-t border-[var(--platform-subpanel-border)] px-4 py-4 sm:px-5';
 
-  const closeButtonClasses = isPixel
-    ? 'rounded-full border border-white/10 bg-black/20 p-2 text-zinc-400 transition-colors hover:text-white disabled:cursor-not-allowed disabled:opacity-45'
-    : 'platform-icon-button disabled:cursor-not-allowed disabled:opacity-45';
-
   return (
     <div
       className={joinClassNames(overlayClasses, zIndexClassName, overlayClassName)}
@@ -183,15 +179,12 @@ function UnifiedModalContent({
             ) : null}
           </div>
           {showCloseButton ? (
-            <button
-              type="button"
-              aria-label={closeLabel}
+            <PlatformModalCloseButton
+              label={closeLabel}
               onClick={onClose}
               disabled={closeDisabled}
-              className={closeButtonClasses}
-            >
-              <X className="h-4 w-4" />
-            </button>
+              variant={isPixel ? 'pixel' : 'platformIcon'}
+            />
           ) : null}
         </div>
         <div className={joinClassNames(bodyClasses, bodyClassName)}>