feat: route structure, providers, layouts, and placeholder pages

app/providers.tsx

@@ -0,0 +1,20 @@
+"use client"
+
+import { QueryClient, QueryClientProvider } from "@tanstack/react-query"
+import { useState } from "react"
+
+export function Providers({ children }: { children: React.ReactNode }) {
+  const [queryClient] = useState(
+    () =>
+      new QueryClient({
+        defaultOptions: {
+          queries: {
+            staleTime: 60 * 1000,
+            refetchOnWindowFocus: false,
+          },
+        },
+      }),
+  )
+
+  return <QueryClientProvider client={queryClient}>{children}</QueryClientProvider>
+}