REFACTOR(longhorn): migrate monitoring PVCs

- from local-path to Longhorn
- Grafana: 2Gi (replica=3)
- Loki: 10Gi (replica=3)
- Alertmanager: 1Gi (replica=3)
- Prometheus: 5Gi (replica=3)
- Use dedicated 50GB Longhorn storage on each node

alertmanager/helm-values/alertmanager.yaml

@@ -6,7 +6,7 @@ fullnameOverride: alertmanager
 persistence:
   enabled: true
   size: 1Gi
-  storageClass: local-path
+  storageClass: longhorn  # Migrated from local-path to Longhorn (replica=3)
 
 resources:
   requests:

grafana/helm-values/grafana.yaml

@@ -13,7 +13,7 @@ admin:
 persistence:
   enabled: true
   size: 2Gi
-  storageClass: local-path
+  storageClass: longhorn  # Migrated from local-path to Longhorn (replica=3)
 
 initChownData:
   enabled: false

loki/helm-values/loki.yaml

@@ -40,7 +40,7 @@ singleBinary:
   persistence:
     enabled: true
     size: 10Gi
-    storageClass: local-path
+    storageClass: longhorn  # Migrated from local-path to Longhorn (replica=3)
   resources:
     requests:
       cpu: 15m  # Reduced from 50m based on actual usage (10m)

prometheus/helm-values/kube-prometheus-stack.yaml

@@ -44,7 +44,7 @@ prometheus:
     storageSpec:
       volumeClaimTemplate:
         spec:
-          storageClassName: local-path
+          storageClassName: longhorn  # Migrated from local-path to Longhorn (replica=3)
           accessModes: ["ReadWriteOnce"]
           resources:
             requests: