Deprecate finalize_model_tidyclust() and finalize_workflow_tidyclust()

[EmilHvitfeldt]

finalize_model_tidyclust() and finalize_workflow_tidyclust() are now fully redundant — tune's own versions already support cluster_spec natively.

Specifically:

• tune::finalize_model() explicitly checks inherits(x, "cluster_spec") in its guard condition, so it already handles tidyclust models.
• tune::finalize_workflow() calls finalize_model() internally, so it also works with cluster specs automatically.

Steps

1. Verify that tune::finalize_model() and tune::finalize_workflow() produce identical results to the tidyclust versions for cluster_spec objects.
2. Deprecate finalize_model_tidyclust() and finalize_workflow_tidyclust() using the lifecycle package, pointing users to the tune equivalents.
3. Remove the deprecated functions in a future breaking release.

Note

This is a breaking change for any users calling finalize_model_tidyclust() or finalize_workflow_tidyclust() directly. The deprecation period allows them to migrate to tune::finalize_model() and tune::finalize_workflow().