🔧(demo) update demo app to ts config file, customize one token

Showcase a situation where we want to customize a component's design token.

apps/demo/src/main.tsx

@@ -8,8 +8,8 @@ ReactDOM.createRoot(document.getElementById("root") as HTMLElement).render(
   <React.StrictMode>
     <div className="center">
       <h1 className="test">Cunningham Demo.</h1>
-      <Button />
-      <h3>Primary color is {tokens.colors.primary}</h3>
+      <Button>World best button.</Button>
+      <h3>Primary color is {tokens.theme.colors.primary}</h3>
     </div>
   </React.StrictMode>
 );