Realizability Checker UI Tick Boxes

[mluckcuck]

This is a minor issue, but the first thing that jumped out at me when I started using the Realisability Checker; there are two options for how the check works: Compositional and Monolithic. But they are mutually exclusive. But the UI has tick boxes (check boxes) to select them.

It is helpful that one tick box is unticked when the other is ticked, but it should just be radio buttons. Using radio buttons would be a much clearer visual signal to the user that these options are mutually exclusive.

[anmavrid]

Thanks Matt for the great suggestion.