调整首页当前账号卡片宽度比例

变更项：

1. 仅调整首页顶部 Hero 区栅格比例，从 9:15 改为 8:16。

2. 缩小当前账号卡片宽度，提升右侧核心指标区的展示空间。

3. 未调整下方新增用户数、群渗透率、群健康分区域布局。

admin/dashboard/templates/index.html

@@ -18,7 +18,7 @@
     </div>
 
     <el-row :gutter="16" class="hero-row">
-        <el-col :span="9">
+        <el-col :span="8">
             <el-card class="hero-card hero-card--profile" shadow="hover">
                 <div v-if="currentUser.success" class="hero-profile">
                     <div class="hero-profile-top">
@@ -53,7 +53,7 @@
             </el-card>
         </el-col>
 
-        <el-col :span="15">
+        <el-col :span="16">
             <el-row :gutter="16" class="metric-grid">
                 <el-col :span="8">
                     <el-card class="metric-card metric-card--primary" shadow="hover">
@@ -102,6 +102,9 @@
     </el-row>
 
     <el-row :gutter="16" class="metric-extended-row">
+        <el-col :span="9" class="metric-extended-row-placeholder"></el-col>
+        <el-col :span="15" class="metric-extended-main">
+            <el-row :gutter="16" class="metric-grid metric-grid--extended">
                 <el-col :span="8">
                     <el-card class="metric-card metric-card--soft" shadow="hover">
                         <div class="metric-label">新增用户数</div>
@@ -124,6 +127,8 @@
                     </el-card>
                 </el-col>
             </el-row>
+        </el-col>
+    </el-row>
 
     <el-row :gutter="16" class="stats-highlight-row">
         <el-col :span="8">
@@ -945,6 +950,14 @@
         display: flex;
     }
 
+    .metric-extended-main {
+        width: 100%;
+    }
+
+    .metric-grid--extended .el-col {
+        margin-bottom: 0;
+    }
+
     .metric-card {
         min-height: 106px;
         width: 100%;
@@ -1108,6 +1121,10 @@
     }
 
     @media (max-width: 1200px) {
+        .metric-extended-row-placeholder {
+            display: none !important;
+        }
+
         .hero-row > .el-col,
         .metric-extended-row > .el-col,
         .stats-highlight-row > .el-col,