Docs update / basic upkeep

Problem/Motivation

I have a few tiny changes to include to make future development easier.

* I've added the Vocabulary section that helped me understand the landscape of the problemspace.
* I've added a gitignore that we can expand upon in the future.
* Perhaps controversially, I've added a Claude.md file that was generated by Claude Code. It helps provide context whenever using an AI bot (not just Claude) when having conversations about the code.