Route handling + Added main layout.

components/Sidebar.tsx

@@ -0,0 +1,13 @@
+import { useSession } from "next-auth/react";
+
+export default function Sidebar() {
+  const { data: session, status } = useSession();
+
+  const user = session?.user;
+
+  return (
+    <div className="fixed bg-gray-100 top-0 bottom-0 left-0 w-80">
+      <p>{user?.name}</p>
+    </div>
+  );
+}