Input record for FlowManager::create_managed. The runtime owns
id/revision/timestamps; everything else is supplied by the caller
(controller, agent tool, or skill author).
Record step observation from an externally-driven task. Used in mirrored
mode: the host sees a task event on NATS (or another bus), translates it
to a StepObservation, and feeds it to the manager so the flow’s
flow_steps view stays in sync without owning task creation.