REFACTOR(repo): restructure infra folder structure

- Remove argocd/, helm-values/, ingress/ subdirectories
- Move files to parent directory with standardized names
- Add namespace.yaml to all apps with Goldilocks labels
- Preserve vault/ subdirectories (falco, velero)
- Update main kustomization.yaml to reference argocd.yaml files directly
- Comment out argocd.yaml in each app's kustomization.yaml to prevent
  circular reference

Applications restructured:
- cert-manager (2 ArgoCD apps)
- external-secrets
- reloader
- vault (2 ArgoCD apps)
- velero (2 ArgoCD apps)
- falco
- cnpg
- haproxy
- metallb
- vpa
- argocd

vpa/kustomization.yaml

@@ -2,5 +2,6 @@ apiVersion: kustomize.config.k8s.io/v1beta1
 kind: Kustomization
 
 resources:
-  # ArgoCD Application 리소스는 infrastructure/kustomization.yaml에서 관리
-  # - argocd/vpa.yaml
+  # argocd.yaml은 수동으로 관리 (순환 참조 방지)
+  # - argocd.yaml
+  - namespace.yaml