Wraps Mobus.Stepwise.Components.StepwiseProjection and converts the
resulting Mobus.Stepwise.Projection into WorkflowStem.Projection.
Delegates all projection logic (ordered_steps, available_events, ui_for, subscriptions_for, build_extensions) to the foundation, then wraps the struct for workflow_stem consumers.
See Mobus.Stepwise.Components.StepwiseProjection for the underlying
implementation.