Harper Desktop keeps running after I quit it.

I noticed that Harper Desktop was sometimes using quite a lot of CPU though it was in the background. I thought my laptop might run a bit cooler if I quit it and then I'd know if it was using too much CPU.

Bun after quitting it from the menu I looked in Activity Monitor and saw it still running. You can see it's here but its icon is no longer in the menu bar.

I suspect this is due to it actually having two processes and when we quit we only quit the one with its "activation policy" set to `.desktop` but the other, which has its activation policy set to `.accessory` still runs without doing anything useful.

Reproduce the issue by quitting Harper Desktop from its menu, then check Activity Monitor for the remaining process. Start by tracing the desktop quit handling and the processes using the `.desktop` and `.accessory` activation policies; done means quitting leaves no Harper process running.

Written by the indexing model from the issue text.