perf: dashboard 默认6小时查询(减73%扫描行) + 7天自动清理 + 5分钟自动刷新

frontend/src/components/dashboard/Dashboard.tsx

@@ -62,7 +62,7 @@ export function Dashboard() {
           console.error('Failed to fetch dashboard releases:', e);
           return null;
         }),
-        dashboardStatsApi.getMetrics(24).catch((e) => {
+        dashboardStatsApi.getMetrics(6).catch((e) => {
           console.error('Failed to fetch metrics:', e);
           return [];
         }),
@@ -85,6 +85,9 @@ export function Dashboard() {
 
   useEffect(() => {
     refreshData();
+    // 每 5 分钟自动刷新
+    const interval = setInterval(refreshData, 5 * 60 * 1000);
+    return () => clearInterval(interval);
   }, [refreshData]);
 
   if (initialLoading) {