Review fixes for the failure screen: the enabling sentence needs the
change to have asked for enabling (ChangeResult.enabled), a run whose
first chunk arrives after the answer is kept in the settled dialog
instead of being dropped, and the no-run note says the details received
no terminal output, only on a settled screen. The enabling sentence also
stands alone when there is no other reason, the test fixture no longer
produces install failures at the enable stage, and the README records the
settled-log limits.