feat(backup-system): migración completa a GitOps

- CronJob rclone-mega-backup entra en git (solo existía imperativo)
- Scripts backup.sh/verify.sh/rclone-mega.sh como ConfigMap backup-scripts
  (antes hostPath /data/backups/scripts — cambios ahora pasan por git+ArgoCD)
- rclone.conf vía InfisicalStaticSecret (homelab/prod//backup-system → RCLONE_CONF),
  sustituye al hostPath de ~/.config/rclone/rclone.conf
- Imágenes pinneadas: rclone 1.74.3, bitnami/kubectl por digest (v1.36.2)
- ClusterRole/CRB de backup-sa entran en git
- Application ArgoCD backup-system (auto-sync + prune + selfHeal)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

backup-system/argocd-app.yaml

@@ -0,0 +1,23 @@
+apiVersion: argoproj.io/v1alpha1
+kind: Application
+metadata:
+  name: backup-system
+  namespace: argocd
+  annotations:
+    notifications.argoproj.io/subscribe.on-sync-failed.telegram: "5138407666"
+    notifications.argoproj.io/subscribe.on-health-degraded.telegram: "5138407666"
+spec:
+  project: default
+  source:
+    repoURL: https://git.chemavx.xyz/chemavx/k8s-manifests
+    targetRevision: HEAD
+    path: backup-system
+  destination:
+    server: https://kubernetes.default.svc
+    namespace: backup-system
+  syncPolicy:
+    automated:
+      prune: true
+      selfHeal: true
+    syncOptions:
+      - CreateNamespace=true