feat: 前端指标体系增强 — Dashboard/Metrics API、2×4 统计区、趋势图面积+异常标记、连续状态列

- 新增 GET /api/dashboard 合并原 summary+targets 首屏接口
- 新增 GET /api/targets/:id/metrics 合并原 stats+trend 概览接口
- 后端指标纯函数：可用率、百分位、故障段分析、连续状态、UTC 小时分桶
- ProbeStore 窗口取数方法替代全量历史查询
- SummaryCards 扩展为 4 卡片（新增异常事件数）+ 数据新鲜度展示
- 表格新增「连续」列（Tag 渲染 capped 状态）
- OverviewTab 重构为 2×4 Statistic 多维度布局
- TrendChart 改为延迟范围面积图 + 红色异常标记点
- 删除旧路由（summary/targets/trend）和 computeTrendStats
- 同步 delta specs 到主 specs 并归档变更

src/web/app.tsx

@@ -3,28 +3,25 @@ import { Alert, Loading, Typography } from "tdesign-react";
 import { SummaryCards } from "./components/SummaryCards";
 import { TargetBoard } from "./components/TargetBoard";
 import { TargetDetailDrawer } from "./components/TargetDetailDrawer";
-import { useSummary, useTargets } from "./hooks/use-queries";
+import { useDashboard } from "./hooks/use-queries";
 import { useTargetDetail } from "./hooks/use-target-detail";
 
 export function App() {
-  const { data: summary, error: summaryError, isLoading: summaryLoading } = useSummary();
-  const { data: targets, error: targetsError, isLoading: targetsLoading } = useTargets();
+  const { data: dashboard, error: dashboardError, isLoading: dashboardLoading } = useDashboard();
   const {
     closeDrawer,
     handlePageChange,
     handleTimeChange,
     historyData,
     historyLoading,
+    metricsData,
+    metricsLoading,
     openDrawer,
     selectedTarget,
     timeFrom,
     timeTo,
-    trendData,
-    trendLoading,
   } = useTargetDetail();
 
-  const error = summaryError ?? targetsError;
-
   return (
     <main className="dashboard">
       <header className="dashboard-header">
@@ -32,14 +29,14 @@ export function App() {
         <Typography.Text theme="secondary">统一拨测平台</Typography.Text>
       </header>
 
-      {error && <Alert closeBtn message={`请求失败: ${error.message}`} theme="error" />}
+      {dashboardError && <Alert closeBtn message={`请求失败: ${dashboardError.message}`} theme="error" />}
 
-      {summaryLoading && targetsLoading ? (
+      {dashboardLoading ? (
         <Loading />
       ) : (
         <>
-          <SummaryCards summary={summary ?? null} />
-          <TargetBoard onTargetClick={openDrawer} targets={targets ?? []} />
+          <SummaryCards summary={dashboard?.summary ?? null} />
+          <TargetBoard onTargetClick={openDrawer} targets={dashboard?.targets ?? []} />
         </>
       )}
 
@@ -47,14 +44,14 @@ export function App() {
         historyData={historyData}
         historyLoading={historyLoading}
         key={selectedTarget?.id}
+        metricsData={metricsData}
+        metricsLoading={metricsLoading}
         onClose={closeDrawer}
         onPageChange={handlePageChange}
         onTimeChange={handleTimeChange}
         target={selectedTarget}
         timeFrom={timeFrom}
         timeTo={timeTo}
-        trendData={trendData}
-        trendLoading={trendLoading}
       />
     </main>
   );