test(argocd): add label to vault app to verify GitOps flow

Add test-gitops=true label to vault Application to demonstrate end-to-end
GitOps sync: commit push → ArgoCD detects change → applies label to live app.
Tests that root-app watches k8s/argocd/apps/ and propagates changes.

k8s/argocd/apps/1-wave-1.yaml

@@ -3,6 +3,8 @@ kind: Application
 metadata:
   name: vault
   namespace: argocd
+  labels:
+    test-gitops: "true"
   annotations:
     argocd.argoproj.io/sync-wave: "1"
 spec: