feat: Add ArgoCD Application manifest for nebari-operator deployment

[viniciusdc]

Summary

Adds ArgoCD Application manifest to deploy the NebariApp Operator (formerly NIC Operator) as part of the Nebari foundational infrastructure. This enables GitOps-based deployment and management of the operator across Nebari clusters.

Testing

Verify ArgoCD Application

# Check Application status
kubectl get application nebari-operator -n argocd

# View sync status
argocd app get nebari-operator

# Check Application health
argocd app status nebari-operator

Verify Operator Deployment

# Check operator pods
kubectl get pods -n nebari-operator-system

# Check operator logs
kubectl logs -n nebari-operator-system -l control-plane=controller-manager -f

# Verify CRDs installed
kubectl get crd nebariapps.reconcilers.nebari.dev

# Test NebariApp creation
kubectl apply -f - <<EOF
apiVersion: reconcilers.nebari.dev/v1
kind: NebariApp
metadata:
  name: test-app
  namespace: default
spec:
  hostname: test.nebari.local
  service:
    name: test-service
    port: 8080
EOF

Verify Metrics

# Port-forward to metrics endpoint
kubectl port-forward -n nebari-operator-system \
  deployment/nebari-operator-controller-manager 8080:8080

# Check metrics
curl http://localhost:8080/metrics

[viniciusdc]

I think this is wrong

[dcmcand]

Note: the kustomization.yaml resource URL needed to be corrected. Two issues with the original:

1. dist/install.yaml doesn't exist in the nebari-operator repo — the operator uses standard kubebuilder layout with manifests under config/default/
2. raw.githubusercontent.com URLs don't work as kustomize resources — kustomize tries to git fetch from them and fails

The correct kustomize remote resource format is:

resources:
  - https://github.com/nebari-dev/nebari-operator.git/config/default?ref=main

instead of:

resources:
  - https://raw.githubusercontent.com/nebari-dev/nebari-operator/main/dist/install.yaml