refactor(k8s): Reorganize into 5-layer structure with production kustomizations

k8s/infrastructure/longhorn/kustomization.yaml

@@ -0,0 +1,5 @@
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+namespace: longhorn-system
+resources: []
+# Longhorn deployed via Helm chart (values in parent layer)

k8s/infrastructure/longhorn/longhorn-servicemonitor.yaml

@@ -0,0 +1,23 @@
+# k8s/longhorn/longhorn-servicemonitor.yaml
+# Longhorn is deployed via raw manifest (cluster-config/longhorn_bootstrap.sh), not
+# Helm, so there's no chart values toggle for metrics — the manager already exposes
+# them on the existing longhorn-backend service (port 9500); this just wires Prometheus
+# to it. longhorn_volume_robustness is the availability signal (degraded/faulted).
+apiVersion: monitoring.coreos.com/v1
+kind: ServiceMonitor
+metadata:
+  name: longhorn-manager
+  namespace: longhorn-system
+  labels:
+    app: longhorn-manager
+spec:
+  selector:
+    matchLabels:
+      app: longhorn-manager
+  namespaceSelector:
+    matchNames:
+      - longhorn-system
+  endpoints:
+    - port: manager
+      interval: 30s
+      scrapeTimeout: 10s