feat: Add material UI and theme

[wesbillman]

<Container maxWidth='sm' sx={{ m: 4 }}>
  <Stack spacing={2}>
    <Button variant='contained'>Sample MUI Button</Button>
    <Button variant='contained'>Sample MUI Button</Button>
  </Stack>
</Container>

Produces this UI:

[alecthomas]

Out of curiosity, what is this giant data object?

[wesbillman]

I think it's setting standard theme properties on the components. Like default border radii on a button, etc.