Capability runner adapter for workflow_stem consumers.
Relationship to the foundation
The stepwise engine path delegates to Mobus.Stepwise.Engine, which uses
Mobus.Stepwise.Capabilities internally. That module reads from
:mobus_stepwise config — bridged at startup by WorkflowStem.Application.
This module (WorkflowStem.Capabilities) remains for the FSM and Flow
engine paths, which have their own capability execution flows. It reads
from :workflow_stem config directly (not bridged).
Consumers that only use the stepwise engine can ignore this module;
configure :workflow_stem, :capability_runner_adapter and the bridge
handles the rest. FSM/Flow consumers call execute/3 here directly.