Paginated Auto Tune audit history for an all-purpose cluster

Paginated response wrapper for the Auto Tune history endpoint.

Matches the existing Databricks response convention (total_count / page / page_size / total_pages) rather than fastapi_pagination.Page[T] — none of the other Databricks endpoints in this router use the latter.

Shared by the job-cluster history endpoint, which populates every item's reason_detail, and the sibling all-purpose-cluster history endpoint (cluster_auto_tune_api.py), which intentionally does not — that surface's items always carry reason_detail=None and the FE falls back to actionable_message / reason. Wiring reason_detail into the cluster endpoint too is a candidate follow-up, not done here.