homeassistant: cover the secret reference, document the content gap

Home Assistant reads configuration.yaml, http-config.yaml and
recorder-config.yaml from a 1Password-backed Secret, mounted with subPath.
Two different gaps hide behind that, and only one of them can be closed.

Repointing secrets.configSecretRef at a different vault item used to leave the
running pod on the old configuration. That is now covered: the pod template
carries checksum/secret-ref over the rendered OnePasswordItem. The annotation
is named apart from checksum/config on purpose - it only promises that the
config source changed, not the config itself - matching the pattern
minecraft-server introduced.

Changing the CONTENT of the item in the vault still does not restart anything,
and cannot: Helm never sees the content, so there is nothing to hash. The
operator's own auto-restart annotation is no way out either - onepassword-
operator 1.12.0 enumerates exactly one workload type in its secret-update
handler (appsv1.DeploymentList) and this workload is a StatefulSet, so the
annotation would be a silent no-op advertising a guarantee it cannot keep. It
is deliberately not set. values.yaml states the limitation and the manual
rollout restart it requires; the README guideline records the operator finding,
the annotation precedence trap, and the checksum/secret-ref pattern so neither
is rediscovered the hard way.

Major bump: runtime behavior changes - changing the secret reference now costs
a restart. For this release the effect is preventive, since it currently runs
at zero replicas via scaleDown.

homeassistant/templates/homeassistant.sfs.yaml

@@ -15,6 +15,18 @@ spec:
       labels:
         app: "{{ .Release.Name }}-{{ .Chart.Name }}"
       name: "{{ .Release.Name }}-{{ .Chart.Name }}-sfs"
+      annotations:
+        # Deliberately NOT a hash of the secret's content: the Kubernetes Secret
+        # is materialized by the 1Password operator, so Helm never sees what is
+        # in it. This hash covers the rendered OnePasswordItem, i.e. the op://
+        # item path - repointing secrets.configSecretRef at a different item now
+        # takes effect instead of silently leaving the old configuration in the
+        # running pod. A change of the item's CONTENT inside the vault is not
+        # covered; see the comment on secrets in values.yaml for why that gap
+        # cannot be closed here and what it means operationally.
+        # The name differs from checksum/config on purpose - that one promises
+        # "the config changed", this one only "the config source changed".
+        checksum/secret-ref: {{ include (print $.Template.BasePath "/homeassistant-core-config.secret.yaml") . | sha256sum }}
     spec:
       automountServiceAccountToken: false
       securityContext: