feat: replace login route with auth modal

- Add AuthModal to root layout driven by ?modal=auth search param
- Update multiplayer and play beforeLoad redirects to use modal
- Update NavAuth and Hero links to use modal
- Delete login route and NavLogin component

apps/web/src/routes/multiplayer.tsx

@@ -14,7 +14,10 @@ export const Route = createFileRoute("/multiplayer")({
   beforeLoad: async () => {
     const { data: session } = await authClient.getSession();
     if (!session) {
-      throw redirect({ to: "/login" });
+      throw redirect({
+        to: "/",
+        search: { modal: "auth", redirect: "/multiplayer" },
+      });
     }
     return { session };
   },