Investigate using Tree-Sitter as a syntax highlighter

Tree-Sitter is a modern parsing system that is faster and more accurate than TextMate-grammars.

**Resources:**
- [`vscode-tree-sitter`](https://www.npmjs.com/package/vscode-tree-sitter) for VSCode extension support
- [`tree-sitter-kotlin`](https://www.npmjs.com/package/tree-sitter-kotlin) for Kotlin syntax highlighting

**See also:**
- [the issue tracking upstream support for tree-sitter](https://github.com/microsoft/vscode/issues/50140)

Start by reviewing the linked vscode-tree-sitter and tree-sitter-kotlin resources, then read the upstream VS Code issue on Tree-sitter support. The issue names no files, tests, entry points, or acceptance criteria, so the desired implementation and definition of done remain to be established.

Written by the indexing model from the issue text.