feat: NFS provisioner + persistance Prometheus et Grafana

- k8s/infra/nfs-provisioner/ : nfs-subdir-external-provisioner v4.0.18
  StorageClass "nfs" (default), ReclaimPolicy=Retain, server=192.168.10.1
  path=/srv/data/nfs/k8s (export RAID5 déjà existant)
- k8s/apps-of-apps/apps/nfs-provisioner.yaml : Application ArgoCD
- monitoring/values.yaml : persistance activée
  Prometheus: 20Gi sur nfs, Grafana: 2Gi sur nfs

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

k8s/infra/nfs-provisioner/values.yaml

@@ -0,0 +1,16 @@
+nfs:
+  server: 192.168.10.1
+  path: /srv/data/nfs/k8s
+
+storageClass:
+  name: nfs
+  defaultClass: true
+  reclaimPolicy: Retain
+  archiveOnDelete: false
+
+resources:
+  requests:
+    cpu: 50m
+    memory: 64Mi
+  limits:
+    memory: 128Mi