Consider alternatives to tree-sitter

I’m filing quickly on mobile ahead of our check in, but briefly:

- tree-sitter adds a fair bit of tooling complexity
- And page weight
- It’s unclear that we benefit from its most compelling distinct features like incremental parsing
- While the grammar is stable, it’s a constant build time drag in CI
- Other tools might be better suited for eg TypeScript integration (as in type gen for aspects of the syntax we’re concerned with)

I briefly explored [Ohm](https://ohmjs.org/) over the weekend and it’s a pretty compelling alternative option (albeit with some reservations around maturity). Beyond its TS support, I was encouraged by how easy it was to build a cromulent XPath grammar, and how much more closely it matches the grammar from the spec.

The issue names tree-sitter and Ohm but mentions no files, tests, or entry points. Start by mapping where tree-sitter affects tooling, page weight, CI, and TypeScript integration; done would require a decided replacement or documented conclusion.

Written by the indexing model from the issue text.