Hard code in a mapping of Zone Categories to Colors and use it in the UI

[mshenfield]

In the design, zones are shown with a friendly color coding.

In general, we should have a consistent mapping of Zone Categories to colors. The full list of Zone Categories can be found in the code here.

I'm familiar with d3-color, which is thoughtful about providing space between colors, but if there's something you prefer (or you want to learn more) feel free to use what you find is good.