add pvc-autoresizer for automatic PVC expansion before volumes fill up [ci skip]

Deploy topolvm/pvc-autoresizer controller that monitors kubelet_volume_stats
via Prometheus and auto-expands annotated PVCs. Annotated all 9 block-storage
PVCs (proxmox-lvm) with per-PVC thresholds and max limits. Updated PVFillingUp
alert to critical/10m (means auto-expansion failed) and added PVAutoExpanding
info alert at 80%.

stacks/monitoring/modules/monitoring/prometheus.tf

@@ -4,6 +4,11 @@ resource "kubernetes_persistent_volume_claim" "prometheus_server_pvc" {
   metadata {
     name      = "prometheus-data-proxmox"
     namespace = kubernetes_namespace.monitoring.metadata[0].name
+    annotations = {
+      "resize.topolvm.io/threshold"     = "90%"
+      "resize.topolvm.io/increase"      = "10%"
+      "resize.topolvm.io/storage_limit" = "500Gi"
+    }
   }
 
   spec {

stacks/monitoring/modules/monitoring/prometheus_chart_values.tpl

@@ -801,13 +801,20 @@ serverFiles:
               severity: warning
             annotations:
               summary: "Disk {{ $labels.mountpoint }} on {{ $labels.instance }}: {{ $value | printf \"%.1f\" }}% free (threshold: 10%)"
+          - alert: PVAutoExpanding
+            expr: (kubelet_volume_stats_used_bytes / kubelet_volume_stats_capacity_bytes) * 100 > 80 and kubelet_volume_stats_capacity_bytes < 1099511627776
+            for: 5m
+            labels:
+              severity: info
+            annotations:
+              summary: "PV {{ $labels.persistentvolumeclaim }} in {{ $labels.namespace }}: {{ $value | printf \"%.0f\" }}% used — auto-expansion should trigger"
           - alert: PVFillingUp
             expr: (kubelet_volume_stats_used_bytes / kubelet_volume_stats_capacity_bytes) * 100 > 95 and kubelet_volume_stats_capacity_bytes < 1099511627776
-            for: 30m
+            for: 10m
             labels:
-              severity: warning
+              severity: critical
             annotations:
-              summary: "PV {{ $labels.persistentvolumeclaim }} in {{ $labels.namespace }}: {{ $value | printf \"%.0f\" }}% used (threshold: 95%)"
+              summary: "PV {{ $labels.persistentvolumeclaim }} in {{ $labels.namespace }}: {{ $value | printf \"%.0f\" }}% used — auto-expansion may have failed"
           - alert: PVPredictedFull
             expr: predict_linear(kubelet_volume_stats_used_bytes[6h], 3600*24) > kubelet_volume_stats_capacity_bytes
             for: 1h