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

adguardhome/templates/deployment.yaml

@@ -46,16 +46,9 @@ spec:
           resources:
             {{- toYaml .Values.resources | nindent 12 }}
           volumeMounts:
-            - name: work
-              mountPath: /opt/adguardhome/work
-            - name: conf
-              mountPath: /opt/adguardhome/conf
+            - name: data
+              mountPath: /opt/adguardhome
       volumes:
-        - name: work
-          hostPath:
-            path: {{ .Values.volumes.work.hostPath }}
-            type: DirectoryOrCreate
-        - name: conf
-          hostPath:
-            path: {{ .Values.volumes.conf.hostPath }}
-            type: DirectoryOrCreate
+        - name: data
+          persistentVolumeClaim:
+            claimName: {{ .Values.persistence.existingClaim | default (printf "%s-data" .Release.Name) }}