feat(per-instance-hook-scoping): scope observability + backup hooks by instance

frontend/src/pages/service-tabs/MetricsTab.tsx

@@ -1,12 +1,9 @@
 /**
  * Prometheus Metrics tab (spec R2.4, R8.2).
  *
- * Lifts the Prometheus status + targets content from the old cross-service
- * ObservabilityPage into an instance-scoped tab. Shows service health and
- * the Node Exporter scrape-targets list.
- *
- * The hooks (usePrometheusStatus, usePrometheusTargets) are global /
- * first-configured for now. Wiring `instance.id` is a follow-up.
+ * Instance-scoped tab showing Prometheus service health.
+ * usePrometheusStatus is scoped by instance.id; usePrometheusTargets
+ * stays global (returns Node Exporter scrape targets for external Prom).
  */
 import { Radio } from "lucide-react";
 import {
@@ -41,15 +38,11 @@ function TargetsTable({ targets }: { targets: PrometheusTarget[] }) {
 }
 
 export function MetricsTab({ instance }: { instance: ServiceInstance }) {
-	// Global / first-configured hooks for now; instance.id scoping is a
-	// follow-up (see file docstring).
-	void instance;
-
 	const {
 		data: status,
 		isLoading: statusLoading,
 		error: statusError,
-	} = usePrometheusStatus();
+	} = usePrometheusStatus(instance.id);
 	const {
 		data: targets,
 		isLoading: targetsLoading,