feat: migrate vso-system to ArgoCD

Migrate Vault Secrets Operator from Terragrunt to ArgoCD/Kustomize.
Deploys vault-secrets-operator v1.2.0 with 3 replicas, plus ClusterRole,
ClusterRoleBindings, and vault-admin ServiceAccount.

Note: static service account tokens (kubernetes.io/service-account-token)
cannot be stored in git; create manually or via Vault after deployment.

💘 Generated with Crush

Assisted-by: Claude Sonnet 4.6 via Crush <crush@charm.land>

apps/base/vso-system/kustomization.yaml

@@ -0,0 +1,9 @@
+---
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+
+resources:
+  - namespace.yaml
+  - serviceaccount_vault-admin.yaml
+  - clusterrole_vault-service-account-admin.yaml
+  - clusterrolebindings.yaml