Issue #3611952: Cancel is offered on a settled order, where cancelling does nothing

Follow-up to #3611922. The order operations offered a Cancel link on any non-cancelled, non-archived order, including completed and no-show ones, where cancelTransaction() is now a no-op, so the link led to a confirm screen that changed nothing. Cancel is now offered only while the order has not settled (reusing the trait's existing settled flag), matching the manager guard. Kernel-tested.