Experiment with rehype-tree-sitter

[humphd]

Our React Markdown renderer uses plugins to parse and alter what it displays, including Rehype:

https://github.com/tarasglek/chatcraft.org/blob/029165e1f53e7aef8d6df1a35dcd1561ee09a6bb/src/components/Markdown.tsx#L62

https://github.com/haze/rehype-tree-sitter is supposedly a good syntax highlighter. What we use now works, but is not well maintained. We could do an experiment to try this.