Initial commit: KiddOs v3 React kiosk

- React 18 + Vite 5 hot-reload OS (800x480 Nord theme)
- 7 apps: Journal, Calculator, Drawing, CodeLab, Clock, Files, Scratch
- Cage + Cog Wayland kiosk, offline localStorage
- Scripts: dev.sh, run-kiosk.sh, run-prod.sh

webapp/src/main.jsx

@@ -0,0 +1,10 @@
+import React from 'react'
+import ReactDOM from 'react-dom/client'
+import App from './App.jsx'
+import './index.css'
+
+ReactDOM.createRoot(document.getElementById('root')).render(
+  <React.StrictMode>
+    <App />
+  </React.StrictMode>
+)