FIX(test): move SealedSecret to overlays

- Remove sealed-argocd-token.yaml from base
- Add overlays/dev/sealed-argocd-token.yaml (namespace: portfolio-dev)
- Add overlays/prod/sealed-argocd-token.yaml (namespace: portfolio)
- Add SealedSecret references to each overlay kustomization.yaml
- SealedSecret includes namespace during encryption, needs per-env management

deploy/k8s/overlays/prod/kustomization.yaml

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