Fix ArgoCD ServerSideDiff permanent OutOfSync diffs

Add explicit CRD/API defaults to manifests that were causing ArgoCD's
SSA dry-run to produce results different from live state:

- HTTPRoutes: add group, kind, weight defaults to parentRefs/backendRefs
- Kyverno ClusterPolicies: add skipBackgroundRequests, allowExistingViolations
- Tetragon TracingPolicies: add return, maxData, resolve, returnCopy defaults
- Gateway certificateRefs: add group="" default
- Guacamole Gateway: add group="" to certificateRefs

Add ignoreDifferences for resources that legitimately differ:
- Cilium cert Secrets (auto-generated, data always differs)
- Istio ValidatingWebhookConfiguration failurePolicy (istiod mutates)
- Crowdsec LAPI Secrets (randomly generated)
- ServiceMonitor/PodMonitor relabeling action defaults
- StatefulSet volumeClaimTemplates apiVersion/kind defaults

Persist argocd-cm ignoreDifferences config in ArgoCD Helm values.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

infrastructure/kyverno/policies/disallow-nodeport.yaml

@@ -11,6 +11,7 @@ spec:
   background: true
   rules:
     - name: disallow-nodeport
+      skipBackgroundRequests: true
       match:
         any:
           - resources:
@@ -23,6 +24,7 @@ spec:
                 - kube-system
                 - istio-system
       validate:
+        allowExistingViolations: true
         message: "NodePort services are not allowed. Use ClusterIP or LoadBalancer."
         pattern:
           spec: