feat: Adding dark mode, cleaning the UI a small bit, adding a link to the API documentation, and linting the code

Signed-off-by: Francisco Javier Arceo <farceo@redhat.com>

llama_stack/ui/app/page.tsx

@@ -1,6 +1,6 @@
 export default function Home() {
   return (
-    <div>
+    <div className="mt-8">
       <h1>Welcome to Llama Stack!</h1>
     </div>
   );