fix(helm): add ipForwarding monitor and prometheusRule to values.yaml.template

CI uses envsubst to generate values.yaml from the template file.
The template was missing the monitors.ipForwarding section and the
entire prometheusRule section, causing helm lint to fail with
"nil pointer evaluating interface {}.enabled".

Author: mattmattox

helm/node-doctor/values.yaml.template

@@ -133,6 +133,76 @@ serviceMonitor:
   # Relabelings
   relabelings: []
 
+# Prometheus PrometheusRule configuration (for Prometheus Operator alerting)
+prometheusRule:
+  # Enable PrometheusRule creation
+  enabled: false
+  # Namespace where PrometheusRule will be created (defaults to release namespace)
+  namespace: ""
+  # Additional labels for PrometheusRule (e.g., for Prometheus Operator discovery)
+  labels: {}
+  # Additional custom rules to add
+  additionalRules: []
+
+  # Critical alerts - require immediate attention
+  critical:
+    enabled: true
+    cniConfigInvalid:
+      for: 5m
+      labels: {}
+      annotations: {}
+    cniUnhealthy:
+      for: 5m
+      labels: {}
+      annotations: {}
+    networkPartitioned:
+      for: 2m
+      labels: {}
+      annotations: {}
+    kubeletUnhealthy:
+      for: 5m
+      labels: {}
+      annotations: {}
+    readOnlyFilesystem:
+      for: 1m
+      labels: {}
+      annotations: {}
+    ipForwardingDisabled:
+      for: 2m
+      labels: {}
+      annotations: {}
+
+  # Warning alerts - should be investigated soon
+  warning:
+    enabled: true
+    dnsResolutionFailed:
+      for: 5m
+    dnsLatencyHigh:
+      for: 10m
+    memoryPressure:
+      for: 10m
+    diskPressure:
+      for: 10m
+    networkDegraded:
+      for: 10m
+    highPeerLatency:
+      for: 10m
+      thresholdMs: 100
+    lowPeerConnectivity:
+      for: 5m
+      thresholdPercent: 90
+    apiServerLatencyHigh:
+      for: 10m
+
+  # Informational alerts - for awareness
+  info:
+    enabled: true
+    highEventRate:
+      for: 5m
+      threshold: 10
+    noMetrics:
+      for: 10m
+
 # Health probe configuration
 probes:
   liveness:
@@ -276,6 +346,14 @@ monitors:
     readOnlyDetection: true
     ioHealthCheck: true
 
+  ipForwarding:
+    enabled: true
+    interval: 30s
+    timeout: 5s
+    checkIPv4: true
+    checkIPv6: true
+    checkPerInterface: false
+
 # Exporters configuration
 exporters:
   kubernetes: