feat: add GitHub Pages landing site

[jmnunezizu]

Summary

• add a Vite, React, and TypeScript landing site under site/
• include original SCUMMKit hero artwork variants, public support/technical/history sections, and trademark disclaimer copy
• add a GitHub Pages workflow that builds site/dist from changes under site/**

Validation

• npm ci
• npm run build
• git diff --check

Notes

• GitHub Pages source should be set to GitHub Actions in the repository settings before deployment.