Public representation of one workflow step execution.
Step runs provide the run timeline needed for inspection, debugging, and replay decisions without exposing internal persistence records directly.
@type status() :: :pending | :running | :completed | :failed
@type t() :: %SquidMesh.StepRun{ attempts: term(), id: term(), input: term(), inserted_at: term(), last_error: term(), output: term(), recovery: term(), status: term(), step: term(), updated_at: term() }