feat(walkthrough): update skill, docs, and add evals

Merge pull request #3 from alexanderop/claude/update-readme-agent-5GJeX

Replace Claude with agent in README to be harness-agnostic

feat(walkthrough): require code snippet on every detail card

feat(walkthrough): collapse summary by default and update docs

feat: update skill description for clarity and onboarding experience

fix: update references from "Claude" to "AI agent" in walkthrough skill descriptions

Add GitHub Actions workflow for GitHub Pages deployment

docs: add live demo example and fix install command

Initial commit: walkthrough skill for Claude Code