feat(grammar): add body item supertype - #33

The run was canceled by @mkatychev.

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: tree-sitter/parse-action@f44ffa94f802024f27e821a72e6f2f3efc5dd521. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/