CycleEventResponse

One activity-feed entry for a cycle (run/step lifecycle event).

Field	Type	Description
`id`required	`string (uuid)`	Event id
`event_type`required	`string`	Lifecycle event type, e.g. step_run.completed
`occurred_at`required	`string (date-time)`	When the event occurred
`severity`	`string \| null`	Event severity (info/warning/error)
`actor`	`string \| null`	Who emitted it (emitted_by); null = system/Archie
`payload`	`object`	Event detail (step_index, step_id, status, duration_ms…) for FE labelling. show nested Empty object.