Retrieves a single event by event_uuid. The response is UUID-only and includes the event's type-specific configuration: email for Send Email / Send Notification, event_http for HTTP POST, tags (tag UUIDs) for Add/Remove Tags, delay/run_on_days/run_at_time for Delay Timer, advance_campaign_link (cls_uuid + keep_after_sequence_ends) for Advance Campaign Link, and event_parameters for Clone Field Data (field_from/field_to) and Suppress Email (suppression_list_id, returned as a UUID). event_parameters is an empty array for event types that carry no extra parameters.