Switch adguardhome/esphome/signal-gateway/zigbee2mqtt to PVC storage

Replaces raw hostPath (/srv/data/<app>) with a local-path PVC per app,
so these apps get proper PVC lifecycle semantics and can have a PVC
backup CronJob (matching what gitea already has) instead of being
unbacked host directories. local-path already lives on the same disk
these hostPaths did, so this isn't a storage-tier change.

adguardhome specifically: consolidates the previous split work/+conf/
hostPath mounts into a single PVC mounted at /opt/adguardhome (its own
default convention), since a real deployment can't run two hostPath
subtrees off one PVC.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01566weDFku8TaRC2CJUPVM1

signal-gateway/templates/deployment.yaml

@@ -39,6 +39,5 @@ spec:
               mountPath: /home/.local/share/signal-cli
       volumes:
         - name: config
-          hostPath:
-            path: {{ .Values.volume.hostPath }}
-            type: DirectoryOrCreate
+          persistentVolumeClaim:
+            claimName: {{ .Values.persistence.existingClaim | default (printf "%s-data" .Release.Name) }}

signal-gateway/templates/pvc.yaml

@@ -0,0 +1,18 @@
+{{- if and .Values.persistence.enabled (not .Values.persistence.existingClaim) }}
+apiVersion: v1
+kind: PersistentVolumeClaim
+metadata:
+  name: {{ .Release.Name }}-data
+  labels:
+    app.kubernetes.io/name: {{ .Chart.Name }}
+    app.kubernetes.io/instance: {{ .Release.Name }}
+spec:
+  accessModes:
+    {{- toYaml .Values.persistence.accessModes | nindent 4 }}
+  {{- with .Values.persistence.storageClass }}
+  storageClassName: {{ . }}
+  {{- end }}
+  resources:
+    requests:
+      storage: {{ .Values.persistence.size }}
+{{- end }}