Function pause 

pub async fn pause(
    guard: &NamespaceGuard,
    caller: &CallerIdentity,
    request: ProtoPauseRequest,
) -> Result<ProtoPauseResponse, WireError>

Handles a decoded pause request (#204).

Resolves the run (latest when omitted) and calls aion::Engine::pause_workflow, returning the run id and its projected Paused status. The Running precondition is the engine’s; the handler surfaces its typed aion::EngineError::InvalidState error verbatim.

Errors

Returns a stable WireError when IDs are missing/malformed, namespace scoping fails, or the engine pause call fails — invalid_state when the run is not Running, not_found for an absent workflow.