Permanently removes soft-deleted schemas and their child objects (tables, attributes) from a datasource. This operation is irreversible.

Requires the alation.ocf.datasource.rdbms.hard_delete.enabled feature flag to be enabled.

If schema_ids is provided in the request body, only those specific soft-deleted schemas and their children will be purged. If the request body is empty, all soft-deleted schemas in the datasource will be purged.

The purge runs asynchronously as a background job. Use the returned job_id with the Jobs API to track progress.