Track CLAUDE.md in-repo; fix stack doc (pgo -> kura) - #31

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/

missing specification for function from_ucs4be/1

missing specification for function to_ucs4be/1

missing specification for function is_visible_ascii/1

missing specification for function is_visible_latin1/1

missing specification for function is_iso646_basic/1

missing specification for function is_ascii/1

missing specification for function is_latin1/1

missing specification for function is_bmpchar/1

missing specification for function is_unicode/1