monitoring: add Grafana dashboards + kube-state-metrics & node-exporter

Dashboards (provisioned via ConfigMaps into Grafana pod, 'K3s Cluster' folder):
- Cluster Overview: per-namespace CPU/mem/net/fs, pod counts, pod health (KSM)
- Pods & Services: per-pod CPU/mem/net/fs, throttling, pod status, restarts, PVCs
- Nodes: per-node CPU%/mem%, load average, disk usage, network (node-exporter)
- Control Plane & API Server: request rate, latency p95, 5xx, kubelet/PLEG
- Prometheus Self-Monitoring: ingestion, series, scrape duration, memory

Exporters (auto-scraped via existing kubernetes-service-endpoints job):
- kube-state-metrics: pod/deployment/PVC/replica state (kube_pod_status_phase,
  kube_pod_container_status_restarts_total, kube_persistentvolumeclaim_*)
- node-exporter (DaemonSet, hostNetwork): node_cpu_seconds_total,
  node_memory_*, node_filesystem_*, node_load*, node_network_*

monitoring/grafana-deployment.yaml

@@ -33,6 +33,18 @@ spec:
               mountPath: /var/lib/grafana
             - name: grafana-datasources
               mountPath: /etc/grafana/provisioning/datasources
+            - name: grafana-dashboard-provider
+              mountPath: /etc/grafana/provisioning/dashboards
+            - name: dashboards-cluster-overview
+              mountPath: /var/lib/grafana/dashboards/cluster-overview
+            - name: dashboards-pods
+              mountPath: /var/lib/grafana/dashboards/pods
+            - name: dashboards-nodes
+              mountPath: /var/lib/grafana/dashboards/nodes
+            - name: dashboards-control-plane
+              mountPath: /var/lib/grafana/dashboards/control-plane
+            - name: dashboards-prometheus
+              mountPath: /var/lib/grafana/dashboards/prometheus
           resources:
             requests:
               memory: "256Mi"
@@ -47,3 +59,21 @@ spec:
         - name: grafana-datasources
           configMap:
             name: grafana-datasources
+        - name: grafana-dashboard-provider
+          configMap:
+            name: grafana-dashboard-provider
+        - name: dashboards-cluster-overview
+          configMap:
+            name: grafana-dashboard-cluster-overview
+        - name: dashboards-pods
+          configMap:
+            name: grafana-dashboard-pods
+        - name: dashboards-nodes
+          configMap:
+            name: grafana-dashboard-nodes
+        - name: dashboards-control-plane
+          configMap:
+            name: grafana-dashboard-control-plane
+        - name: dashboards-prometheus
+          configMap:
+            name: grafana-dashboard-prometheus