Add a global keyboard shortcut in macOS

In macOS, it would be very useful to be able to define a global (system-level) keyboard shortcut to focus the app window and start a new chat. Additionally, it would be nice to be able to hide the dock icon to reduce clutter.

My preferred mode of operation would be to press a keyboard shortcut whenever I want to initiate a chat, press it again to close the app, and otherwise have the app stay out of the way.