refactor!: finish #209 — runtime strings, Coco (rows, cols), L2HH removal, deletions, merges, refactors, doc fixes - #240

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/