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

esphome/values.yaml

@@ -16,8 +16,13 @@ resources:
 
 hostNetwork: true
 
-volume:
-  hostPath: ""
+persistence:
+  enabled: true
+  existingClaim: ""
+  storageClass: local-path
+  accessModes:
+    - ReadWriteOnce
+  size: 1Gi
 
 ingresses: {}
   # https: