feat: Fullscreen

[mazurroman]

Make the app work in full screen.

Currently the fullscreen button only expands the app horizontally. It would be great to also resize it vertically.

To keep things simple we can keep the page header, so that the logo and the buttons (cmd+k, github, fullscreen, etc) remain.

Acceptance criteria
When in fullscreen mode, the app expands vertically down and fills the entire screen.

[LukaszMMazur]

I would like to work on that

[Joy-Adah]

Is this available?

[stephanniegb]

would like to work on this

[0xSileo]

Started working on it when I saw #106, which has been closed since. I did't see this issue at the time sorry