feat(vault): deploy HashiCorp Vault 2.0.1 with raft HA (5 replicas)

StatefulSet with templated PVC (cephrbd-fast-delete, 10Gi), headless
service for raft cluster communication, HTTPS gateway (443→8200), and
kubernetes provider retry_join for automatic cluster formation.

apps/base/vault/rolebinding.yaml

@@ -0,0 +1,17 @@
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: RoleBinding
+metadata:
+  name: vault
+  namespace: vault
+  labels:
+    app.kubernetes.io/name: vault
+    app.kubernetes.io/instance: vault
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: Role
+  name: vault
+subjects:
+  - kind: ServiceAccount
+    name: vault
+    namespace: vault