feat(后台设置): 设置页重排成网站、班级、开关、判题机几块，保存挪到右上角；班级按年级分组不用再拖；判题机写出多久没动静；AI 小助手（MaxKB 挂件）整个删掉

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/web/index.html

@@ -6,9 +6,6 @@
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <title>判题狗</title>
     <link rel="stylesheet" href="/style.css" />
-    <script>
-      window.localStorage.setItem("maxkbMaskTip", true)
-    </script>
   </head>
   <body>
     <div id="app"></div>