Related: #193

I'd like to embed Studio in my website using an <iframe>. I need to be able to specify a layout, but I can't control the localStorage or the user's account, so I'd like to do something like &layout.data=<base64...> or &layout.url=https://example.org/mylayout.json.

Bonus: API to dynamically change the layout if my website wants to swap between multiple example layouts.