feat: add obsidian-vault PVC (RWX) to infra/databases

Shared by obsidian-server (REST API) and obsidian-ui (noVNC).
ReadWriteMany so both pods can mount on different nodes.

k8s/infra/databases/kustomization.yaml

@@ -10,3 +10,4 @@ resources:
   - temporal-db.yaml
   - memory-db.yaml
   - paperless-db.yaml
+  - obsidian-vault-pvc.yaml

k8s/infra/databases/obsidian-vault-pvc.yaml

@@ -0,0 +1,18 @@
+---
+# Obsidian vault PVC — shared storage for REST API + UI pods
+# ReadWriteMany so both obsidian-server and obsidian-ui can mount simultaneously
+apiVersion: v1
+kind: PersistentVolumeClaim
+metadata:
+  name: obsidian-vault
+  namespace: poimen
+  labels:
+    app.kubernetes.io/name: obsidian-server
+    app.kubernetes.io/part-of: poimen-memory
+spec:
+  accessModes:
+    - ReadWriteMany
+  storageClassName: longhorn
+  resources:
+    requests:
+      storage: 10Gi