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-dashboard-provider.yaml

@@ -0,0 +1,20 @@
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: grafana-dashboard-provider
+  namespace: monitoring
+  labels:
+    app: grafana
+data:
+  provider.yaml: |
+    apiVersion: 1
+    providers:
+      - name: 'k3s-dashboards'
+        orgId: 1
+        folder: 'K3s Cluster'
+        type: file
+        disableDeletion: false
+        updateIntervalSeconds: 30
+        allowUiUpdates: true
+        options:
+          path: /var/lib/grafana/dashboards