Add linting and formatting checks for the grammar

[aspeddro]

Summary

This PR standardizes the code quality tooling used for grammar.js and enforces it in CI.

Changes

• Add the official Tree-sitter ESLint configuration.
• Add Prettier configuration and formatting scripts.
• Format grammar.js consistently with single quotes and trailing commas.
• Add JSDoc types and behavior descriptions for grammar helper functions.
• Add a lint workflow that checks ESLint, formatting, and generated parser consistency.
• Update the Tree-sitter CLI and regenerate parser artifacts.
• Update GitHub Actions and use Node.js 22 for compatibility.
• Configure consistent indentation for corpus test files.
• Add an update-tests script for refreshing corpus expectations.