feat(monitoring): align storage to live pvc, add loki datasource and alerts

Match grafana/alertmanager storageClass to live PVCs to avoid immutable-field failures. Add Loki datasource and LokiDown/AlloyDown alerts.

prometheus-stack/k8s/ingress.yaml

@@ -12,7 +12,6 @@ spec:
       middlewares:
         - name: crowdsec-bouncer
           namespace: crowdsec
-        - name: "security-chain@file"
       services:
         - name: prometheus-stack-grafana
           port: 80