clickhouse: keeper PVC is not deleted after the CR is removed #3057

Describe the bug

After deleting a ClickHouse app CR, the ZooKeeper/keeper data PVC remains, consuming storage permanently.

Environment

• Cozystack version: v1.4.0-rc.2
• Provider: on-prem (bare-metal)

To Reproduce

1. Create a tenant, deploy ClickHouse/test.
2. Wait until Ready.
3. Delete the ClickHouse CR; wait ~120s.
4. kubectl -n <ns> get pvc — the keeper PVC remains.

Expected behaviour
Data PVCs are released (or explicitly cleaned) after the CR is deleted.

Actual behaviour

pvc/default-chk-clickhouse-test-keeper-cluster1-0-0-0   Bound

Additional context

• Root cause: The keeper PVC backs a ClickHouseKeeperInstallation (packages/apps/clickhouse/templates/chkeeper.yaml:65-72, volumeClaimTemplates), reconciled by the clickhouse-keeper-operator. The operator does not delete data PVCs when the CHK CR is removed (data-safety default), and the CRD exposes no persistentVolumeClaimRetentionPolicy equivalent. (The main ClickHouse data PVCs have the same gap.)
• Proposed fix: Add a post-delete PVC cleanup hook packages/apps/clickhouse/templates/hooks/cleanup-pvc.yaml, modeled on the MariaDB hook, selecting PVCs by app={{ .Release.Name }}-keeper (chkeeper.yaml:42) and app.kubernetes.io/instance={{ .Release.Name }}.

Found during a create→delete leak sweep of all 22 apps on Cozystack v1.4.0-rc.2.