update

store/store.js

@@ -0,0 +1,12 @@
+import { configureStore } from '@reduxjs/toolkit';
+import cartReducer from './cartSlice';
+
+export const makeStore = () =>
+  configureStore({
+    reducer: {
+      cart: cartReducer,
+    },
+  });
+
+// Singleton store for the client (App Router renders providers on the client tree).
+export const store = makeStore();