Remove nessus app and fix envoy-gateway OCI chart bug

- Delete nessus Application CRD, manifests, and bootstrap script
- Vendor envoy-gateway Helm chart (v1.6.3) locally to work around
  ArgoCD v3.3.3 Docker Hub OCI resolution bug
- Re-enable auto-sync for envoy-gateway

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

charts/envoy-gateway/templates/leader-election-rbac.yaml

@@ -0,0 +1,55 @@
+apiVersion: rbac.authorization.k8s.io/v1
+kind: Role
+metadata:
+  name: {{ include "eg.fullname" . }}-leader-election-role
+  namespace: '{{ .Release.Namespace }}'
+  labels:
+  {{- include "eg.labels" . | nindent 4 }}
+rules:
+- apiGroups:
+  - ""
+  resources:
+  - configmaps
+  verbs:
+  - get
+  - list
+  - watch
+  - create
+  - update
+  - patch
+  - delete
+- apiGroups:
+  - coordination.k8s.io
+  resources:
+  - leases
+  verbs:
+  - get
+  - list
+  - watch
+  - create
+  - update
+  - patch
+  - delete
+- apiGroups:
+  - ""
+  resources:
+  - events
+  verbs:
+  - create
+  - patch
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: RoleBinding
+metadata:
+  name: {{ include "eg.fullname" . }}-leader-election-rolebinding
+  namespace: '{{ .Release.Namespace }}'
+  labels:
+  {{- include "eg.labels" . | nindent 4 }}
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: Role
+  name: '{{ include "eg.fullname" . }}-leader-election-role'
+subjects:
+- kind: ServiceAccount
+  name: 'envoy-gateway'
+  namespace: '{{ .Release.Namespace }}'