Recreate CLAUDE.md

[thomasp85]

So much cruft has accumulated in that file and a lot is no longer current. Rather than weeding out in it it may be beneficial to simply start a fresh.

[teunbrand]

From https://code.claude.com/docs/en/best-practices:

Child directories: Claude pulls in child CLAUDE.md files on demand when working with files in those directories

I think it would make sense to do this. When I'm thinkering with files in src, I don't need it to be aware or details about other folders.

[teunbrand]

We should maybe also document any recurring design patterns like the trait based implementation for geoms, scales, projection etc.