Add Reader Test App (GUI Markdown Preview)

[ZFordDev]

CoffeeMD includes a tiny “reader” app for testing Markdown rendering visually.
We need to set up the basic Vite-powered preview UI.

Requirements

• Create reader/index.html with:
  • A textarea for Markdown input
  • A preview pane for rendered HTML
• Create reader/main.ts that:
  • Imports CoffeeMD
  • Renders Markdown on input
• Add a basic layout (split view)
• Ensure npm run dev launches the reader

Notes

• No styling required beyond basic layout
• This will be used heavily during engine development