Typed representation of a collaboration agent lifecycle state.
@type status() :: :pending_init | :running | :completed | :errored | :shutdown | :not_found | String.t()
@type t() :: %Codex.Protocol.CollabAgentState{ message: (String.t() | nil) | nil, status: status() }
@spec from_map(map() | atom() | String.t() | t() | nil) :: t()
@spec to_event_value(t()) :: map() | String.t()
@spec to_map(t()) :: map()