feat(scrollycode): add interactive playground overlay with x-ocaml
Each tutorial step gets a "Try it" button that opens a full-screen
overlay containing an x-ocaml editor pre-loaded with all code up to
that step. Users can edit and run the code interactively.
- Add playground button to desktop and mobile step layouts
- Add overlay HTML with x-ocaml web component element
- Add JavaScript to collect step code and open/close overlay
- Add themed CSS for overlay, buttons, and editor styling
- Load x-ocaml.js script for interactive editing
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>