Add React race hub frontend

frontend/src/router.tsx

@@ -0,0 +1,47 @@
+import { createRootRoute, createRoute, createRouter, Outlet, redirect } from '@tanstack/react-router'
+import { Nav } from './components/Nav'
+import { RaceHubPage } from './pages/RaceHubPage'
+
+type RaceHubSearch = {
+  session_key?: number
+}
+
+const rootRoute = createRootRoute({
+  component: () => (
+    <>
+      <Nav />
+      <Outlet />
+    </>
+  ),
+})
+
+const indexRoute = createRoute({
+  getParentRoute: () => rootRoute,
+  path: '/',
+  beforeLoad: () => {
+    throw redirect({ to: '/race-hub', search: {} })
+  },
+})
+
+export const raceHubRoute = createRoute({
+  getParentRoute: () => rootRoute,
+  path: '/race-hub',
+  validateSearch: (search: Record<string, unknown>): RaceHubSearch => {
+    const sessionKey = Number(search.session_key)
+    return Number.isFinite(sessionKey) && sessionKey > 0 ? { session_key: sessionKey } : {}
+  },
+  component: function RaceHubRoute() {
+    const { session_key } = raceHubRoute.useSearch()
+    return <RaceHubPage sessionKey={session_key ?? 0} />
+  },
+})
+
+const routeTree = rootRoute.addChildren([indexRoute, raceHubRoute])
+
+export const router = createRouter({ routeTree })
+
+declare module '@tanstack/react-router' {
+  interface Register {
+    router: typeof router
+  }
+}