Add a tea timer

[cxw42]

Because I use one multiple times a day, and I have TabFern open the entire time I'm logged on. This is my current favorite.

Actually, I have been thinking about adding a hamburger menu at the bottom, since the transparent overlay in Tabs Outliner has tripped me up in the past. A menu would be a good place for a tea timer, since it wouldn't get in anyone else's way.