add firebase, add screen flow

lib/features/cart/data/datasources/cart_remote_datasource.dart

@@ -16,8 +16,8 @@ abstract class CartRemoteDataSource {
   /// Add items to cart
   ///
   /// [items] - List of items with item_id, quantity, and amount
-  /// Returns list of cart items from API
-  Future<List<CartItemModel>> addToCart({
+  /// Returns true if successful
+  Future<bool> addToCart({
     required List<Map<String, dynamic>> items,
   });
 
@@ -47,7 +47,7 @@ class CartRemoteDataSourceImpl implements CartRemoteDataSource {
   final DioClient _dioClient;
 
   @override
-  Future<List<CartItemModel>> addToCart({
+  Future<bool> addToCart({
     required List<Map<String, dynamic>> items,
   }) async {
     try {
@@ -78,8 +78,7 @@ class CartRemoteDataSourceImpl implements CartRemoteDataSource {
         throw const ParseException('Invalid response format from add to cart API');
       }
 
-      // After adding, fetch updated cart
-      return await getUserCart();
+      return true;
     } on DioException catch (e) {
       throw _handleDioException(e);
     } catch (e) {