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/envoy-gateway-service.yaml

@@ -0,0 +1,27 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: envoy-gateway
+  namespace: '{{ .Release.Namespace }}'
+  {{- with .Values.service.annotations }}
+  annotations:
+    {{- toYaml . | nindent 4 }}
+  {{- end }}
+  labels:
+    control-plane: envoy-gateway
+  {{- include "eg.labels" . | nindent 4 }}
+spec:
+  type: {{ .Values.service.type }}
+  selector:
+    control-plane: envoy-gateway
+  {{- include "eg.selectorLabels" . | nindent 4 }}
+  ports:
+  {{- .Values.deployment.ports | toYaml | nindent 2 -}}
+  {{- if .Values.topologyInjector.enabled }}
+  - name: webhook
+    port: 9443
+    targetPort: 9443
+  {{- end }}
+  {{- with .Values.service.trafficDistribution }}
+  trafficDistribution: {{ . }}
+  {{- end }}