feat: story library, player and builder UI

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/main.tsx

@@ -3,6 +3,7 @@ import { createRoot } from "react-dom/client";
 import { createBrowserRouter, RouterProvider } from "react-router";
 import { FlagsProvider } from "./lib/flags";
 import { routes } from "./routes";
+import "./styles.css";
 
 const router = createBrowserRouter(routes);