revert: 移除自定义页面过渡动画，使用默认跳转

- header.php: 删除 pageEnter/pageLeave CSS 动画
- footer.php: 删除 click 拦截和 doTransition JS
- 保留 Logo 动态加载脚本

clientarea/hgcloud/header.php

@@ -17,23 +17,6 @@
     <!-- 模板样式 -->
     <link rel="stylesheet" href="/{$template_catalog}/template/{$public_themes}/css/common/reset.css">
 
-    <!-- 页面过渡动画 -->
-    <style>
-      body {
-        animation: pageEnter 0.35s ease both;
-      }
-      body.page-leaving {
-        animation: pageLeave 0.25s ease both;
-      }
-      @keyframes pageEnter {
-        from { opacity: 0; transform: translateY(8px); }
-        to   { opacity: 1; transform: translateY(0); }
-      }
-      @keyframes pageLeave {
-        from { opacity: 1; transform: translateY(0); }
-        to   { opacity: 0; transform: translateY(-8px); }
-      }
-    </style>
 
     <script src="/{$template_catalog}/template/{$themes}/theme/index.js"></script>