feat: clean landing page

[dwmkerr]

Summary

Create a proper Docusaurus landing page that is clean and minimal.

Inspiration

Clojure for the Brave and True

• Two-column layout: book cover on one side, call-to-action on the other
• Clear buttons: "Read Free Online" | "Amazon" | "No Starch"
• No sidebar clutter - full-width hero section
• Clean, focused design that emphasizes the free online edition

Jest (Docusaurus)

• Two-tone dark theme with accent color (green on dark grey)
• 3D animated element spanning the hero section
• "Follow @jestjs_" social button in hero
• Clean navbar: logo, version dropdown, docs links, language, GitHub, dark mode toggle, search
• Feature grid below the hero
• Social proof section ("Who uses Jest?")

Proposed Design for Effective Shell

Hero Section

• Two-tone color scheme (works in light/dark mode)
• 3D book cover image on one side
• Tagline + description on the other
• CTA buttons: Read for Free | Amazon | No Starch

Navbar (top right)

• GitHub stars badge
• Sponsor link
• Dark mode toggle
• Search

Below the fold

• Brief "What you'll learn" feature cards
• "Who should read this" section

Current State

The current intro page has sidebar navigation which competes with any hero-style layout. We need a proper Docusaurus landing page component that renders without sidebars.

Tasks

• Create src/pages/index.js as proper Docusaurus landing page (no sidebars)
• Move current intro content to /introduction or keep in docs
• Add two-column hero with 3D book cover
• Style CTA buttons: "Read for Free" (primary), "Amazon", "No Starch" (secondary)
• Add GitHub stars widget or badge
• Ensure mobile responsiveness
• Test in both light and dark modes
• Consider shell video/gif recording in hero (link to shellwright)