Update CLUSTER-BUILD.md to include kube-prometheus-stack Helm chart details, enhance observability phase with Grafana ingress configuration, and clarify deployment instructions for monitoring components. Mark tasks as completed for kube-prometheus-stack installation and PVC binding on Longhorn.

clusters/noble/apps/kube-prometheus-stack/namespace.yaml

@@ -0,0 +1,11 @@
+# kube-prometheus-stack — apply before Helm (omit --create-namespace on install).
+# prometheus-node-exporter uses hostNetwork, hostPID, and hostPath (/proc, /sys, /) — incompatible
+# with PSA "baseline"; use "privileged" (same idea as longhorn-system / metallb-system).
+apiVersion: v1
+kind: Namespace
+metadata:
+  name: monitoring
+  labels:
+    pod-security.kubernetes.io/enforce: privileged
+    pod-security.kubernetes.io/audit: privileged
+    pod-security.kubernetes.io/warn: privileged