Add live jupyterlite notebooks for examples

[NickCrews]

I have a working prototype at jupyterlite/jupyterlite#1690 (comment)

[NickCrews]

Done (well, need to merge to main to actually see live) in e89c500

[NickCrews]

the notebook viewer is working, I just need to adjust the example notebook to actually work (we import numpy at the top level even though it is supposed to be an optional dep)