macos: global keyboard shortcut to create new zettel

[AlexW00]

As a user, I want to create new Zettel from anywhere.

So I want to have a configurable global keyboard shortcut that I can press and then create a new Zettel in a new window.

[AlexW00]

also: add some gesture so that when the user moves their mouse to the edge of the screen (or hot corner), a zettel peeks out - when clicked it triggers the same new zettel function as the global keyboard shortcut