优化首页指标展示并修复群唯一用户统计

变更项：

1. 修复首页卡片等高问题，统一用户信息与右侧指标区高度，统一热门用户/群组/插件卡片高度。

2. 首页新增三个分析指标：新增用户数、群渗透率、群健康分，并完成前端数据绑定。

3. 优化仪表盘摘要接口，新增 new_users、avg_group_penetration、group_health_score 返回字段。

4. 修复 t_group_stats.unique_users 统计口径，改为按 group_id+plugin_name+command+user_id 去重统计，避免跨群串数据。

5. 新增 t_group_command_user_stats 表结构及索引，并补充到 init.sql。

admin/dashboard/templates/index.html

@@ -92,9 +92,23 @@
                 </el-col>
                 <el-col :span="8">
                     <el-card class="metric-card metric-card--soft" shadow="hover">
-                        <div class="metric-label">系统运行时间</div>
-                        <div class="metric-value">{% raw %}{{ formattedUptime }}{% endraw %}</div>
-                        <div class="metric-footnote">当前实例持续在线时长</div>
+                        <div class="metric-label">新增用户数</div>
+                        <div class="metric-value">{% raw %}{{ newUsers }}{% endraw %}</div>
+                        <div class="metric-footnote">统计周期内首次触发用户</div>
+                    </el-card>
+                </el-col>
+                <el-col :span="8">
+                    <el-card class="metric-card" shadow="hover">
+                        <div class="metric-label">群渗透率</div>
+                        <div class="metric-value">{% raw %}{{ avgGroupPenetration.toFixed(2) }}{% endraw %}%</div>
+                        <div class="metric-footnote">活跃群触发人数占成员比例（均值）</div>
+                    </el-card>
+                </el-col>
+                <el-col :span="8">
+                    <el-card class="metric-card metric-card--soft" shadow="hover">
+                        <div class="metric-label">群健康分</div>
+                        <div class="metric-value">{% raw %}{{ groupHealthScore.toFixed(2) }}{% endraw %}</div>
+                        <div class="metric-footnote">综合成功率与响应时延评分</div>
                     </el-card>
                 </el-col>
             </el-row>
@@ -256,7 +270,10 @@
                 successRate: 0,
                 activeUsers: 0,
                 activeGroups: 0,
+                newUsers: 0,
                 avgResponseTime: 0,
+                avgGroupPenetration: 0,
+                groupHealthScore: 0,
                 topUsers: [],
                 topGroups: [],
                 topPlugins: [],
@@ -425,7 +442,10 @@
                             this.successRate = parseFloat(data.success_rate) || 0;
                             this.activeUsers = data.active_users || 0;
                             this.activeGroups = data.active_groups || 0;
+                            this.newUsers = data.new_users || 0;
                             this.avgResponseTime = parseFloat(data.avg_response_time) || 0;
+                            this.avgGroupPenetration = parseFloat(data.avg_group_penetration) || 0;
+                            this.groupHealthScore = parseFloat(data.group_health_score) || 0;
                             this.topUsers = data.top_users || [];
                             this.topGroups = data.top_groups || [];
                             this.topPlugins = data.top_plugins || [];
@@ -791,8 +811,21 @@
         margin-bottom: 16px;
     }
 
+    .hero-row,
+    .stats-highlight-row {
+        display: flex;
+        flex-wrap: wrap;
+        align-items: stretch;
+    }
+
+    .hero-row > .el-col,
+    .stats-highlight-row > .el-col {
+        display: flex;
+    }
+
     .hero-card {
         min-height: 228px;
+        height: 100%;
     }
 
     .hero-card--profile {
@@ -894,10 +927,13 @@
 
     .metric-grid .el-col {
         margin-bottom: 16px;
+        display: flex;
     }
 
     .metric-card {
         min-height: 106px;
+        width: 100%;
+        height: 100%;
     }
 
     .metric-card .el-card__body {
@@ -942,6 +978,11 @@
         padding-top: 12px !important;
     }
 
+    .insight-card {
+        width: 100%;
+        height: 100%;
+    }
+
     .section-heading,
     .chart-card-header {
         display: flex;