REFACTOR(app): remove ArgoCD integration

- Remove ArgoCD env vars (ARGOCD_SERVER_URL, ARGOCD_TOKEN, ARGOCD_CA_CERT)
- Delete SealedSecret files (dev/prod)
- Remove SealedSecret references from Kustomization
- App no longer calls ArgoCD API, settings not needed

deploy/k8s/overlays/prod/kustomization.yaml

@@ -6,7 +6,6 @@ namespace: portfolio
 resources:
   - ../../base
   - resourcequota.yaml
-  - sealed-argocd-token.yaml
 
 commonLabels:
   environment: production