feat(ui): server metrics admin dashboard

Adds /admin/server-metrics page mirroring the Database/ClickHouse visibility
rules: sidebar entry gated on capabilities.infrastructureEndpoints, backend
controller now has @ConditionalOnProperty(infrastructureendpoints) and
class-level @PreAuthorize('hasRole(ADMIN)'). Dashboard panels are driven
from docs/server-self-metrics.md via the generic
/api/v1/admin/server-metrics/{catalog,instances,query} API — Server Health,
JVM, HTTP & DB pools, and conditionally Alerting + Deployments when their
metrics appear in the catalog. ThemedChart / Line / Area from the design
system; hooks in ui/src/api/queries/admin/serverMetrics.ts. Not yet
browser-verified against a running dev server — backend IT covers the API
end-to-end (8 tests), UI typecheck + production bundle both clean.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

ui/src/api/queries/admin/serverMetrics.ts

@@ -0,0 +1,113 @@
+import { useQuery } from '@tanstack/react-query';
+import { adminFetch } from './admin-api';
+import { useRefreshInterval } from '../use-refresh-interval';
+
+// ── Types ──────────────────────────────────────────────────────────────
+
+export interface ServerMetricCatalogEntry {
+  metricName: string;
+  metricType: string;
+  statistics: string[];
+  tagKeys: string[];
+}
+
+export interface ServerInstanceInfo {
+  serverInstanceId: string;
+  firstSeen: string;
+  lastSeen: string;
+}
+
+export interface ServerMetricPoint {
+  t: string;
+  v: number;
+}
+
+export interface ServerMetricSeries {
+  tags: Record<string, string>;
+  points: ServerMetricPoint[];
+}
+
+export interface ServerMetricQueryResponse {
+  metric: string;
+  statistic: string;
+  aggregation: string;
+  mode: string;
+  stepSeconds: number;
+  series: ServerMetricSeries[];
+}
+
+export interface ServerMetricQueryRequest {
+  metric: string;
+  statistic?: string | null;
+  from: string;
+  to: string;
+  stepSeconds?: number | null;
+  groupByTags?: string[] | null;
+  filterTags?: Record<string, string> | null;
+  aggregation?: string | null;
+  mode?: string | null;
+  serverInstanceIds?: string[] | null;
+}
+
+// ── Query Hooks ────────────────────────────────────────────────────────
+
+export function useServerMetricsCatalog(windowSeconds = 3600) {
+  const refetchInterval = useRefreshInterval(60_000);
+  return useQuery({
+    queryKey: ['admin', 'server-metrics', 'catalog', windowSeconds],
+    queryFn: async () => {
+      const to = new Date();
+      const from = new Date(to.getTime() - windowSeconds * 1000);
+      const params = new URLSearchParams({ from: from.toISOString(), to: to.toISOString() });
+      return adminFetch<ServerMetricCatalogEntry[]>(`/server-metrics/catalog?${params}`);
+    },
+    refetchInterval,
+  });
+}
+
+export function useServerMetricsInstances(windowSeconds = 3600) {
+  const refetchInterval = useRefreshInterval(60_000);
+  return useQuery({
+    queryKey: ['admin', 'server-metrics', 'instances', windowSeconds],
+    queryFn: async () => {
+      const to = new Date();
+      const from = new Date(to.getTime() - windowSeconds * 1000);
+      const params = new URLSearchParams({ from: from.toISOString(), to: to.toISOString() });
+      return adminFetch<ServerInstanceInfo[]>(`/server-metrics/instances?${params}`);
+    },
+    refetchInterval,
+  });
+}
+
+/**
+ * Run a time-series query against the server_metrics table.
+ *
+ * The window [from, to) is supplied in seconds of "now minus N" so the panel
+ * refreshes automatically at the polling interval without the caller
+ * recomputing timestamps.
+ */
+export function useServerMetricsSeries(
+  request: Omit<ServerMetricQueryRequest, 'from' | 'to'>,
+  windowSeconds: number,
+  opts?: { enabled?: boolean },
+) {
+  const refetchInterval = useRefreshInterval(30_000);
+  return useQuery({
+    queryKey: ['admin', 'server-metrics', 'query', request, windowSeconds],
+    queryFn: async () => {
+      const to = new Date();
+      const from = new Date(to.getTime() - windowSeconds * 1000);
+      const body: ServerMetricQueryRequest = {
+        ...request,
+        from: from.toISOString(),
+        to: to.toISOString(),
+      };
+      return adminFetch<ServerMetricQueryResponse>('/server-metrics/query', {
+        method: 'POST',
+        body: JSON.stringify(body),
+      });
+    },
+    refetchInterval,
+    enabled: opts?.enabled ?? true,
+  });
+}