feat: Close to Tray

[braden-w]

trafficstars

          So glad that you're back and pushing a lot of updates!

If I may kindly remind of the close-to-tray feature of a fork of Whispering, it would be very useful if Whispering could be minimized to the tray instead of exiting when the close button is clicked.

I believe, especially with the latest update that includes the two feedback sounds and the red recording icon in the tray, there's no longer a need to keep Whispering open as a window, and even less so in the foreground.

_Originally posted by @DavidGP in https://github.com/braden-w/whispering/issues/103#issuecomment-2198649557_