Add art to the start page

[domoritz]

The start page could be improved with some kind of interactive art/visualization instead of just the moving gradient.

I like https://2020.webassembly-summit.org/ for example. Maybe we could generate contours as well.

One idea is to use map data for Pittsburgh such as https://anvaka.github.io/city-roads/?q=pittsburgh&areaId=3600188553.

There are also some really great art pieces for inspiration at https://observablehq.com/@makio135/creative-coding.

I do like Voronois: https://observablehq.com/@pstuffa/voronoi-of-voronoi, https://observablehq.com/@mootari/voronoi-borderlands

Blurring is also cool: https://wattenberger.com/blog/react-and-d3

Could maybe use https://ptsjs.org/ as well. They have some cool demos.

Current page design:

[domoritz]

More inspiration https://twitter.com/geo_spatialist/status/1415697538221551616

[domoritz]

Done in #252