Sonny: show a task whose goal check passed apart from one that is only done #362

#326 keeps two of the three endings of a task apart in the roster and in /status:

• done: the turn ended with a reply.
• said nothing: the model ended the turn with nothing to say (empty_completion). That is not a failure, but it is not a reply either.

The third ending comes with goals (#341): the task finished and its check passed. Once goals land, the roster and /status should show that as its own state, such as checked, with the check that passed. A plain done on a task that has a goal should read as "ended, check not run or not passed yet", so the person can always tell "it stopped" from "it did what was asked".

This came from an outside review of #318 and #326.