add firebase, add screen flow

lib/features/cart/domain/repositories/cart_repository.dart

@@ -22,14 +22,13 @@ import 'package:worker/features/cart/domain/entities/cart_item.dart';
 abstract class CartRepository {
   /// Add items to cart
   ///
-  /// [items] - List of cart items to add
   /// [itemIds] - Product ERPNext item codes
   /// [quantities] - Quantities for each item
   /// [prices] - Unit prices for each item
   ///
-  /// Returns list of cart items on success.
+  /// Returns true if successful.
   /// Throws exceptions on failure.
-  Future<List<CartItem>> addToCart({
+  Future<bool> addToCart({
     required List<String> itemIds,
     required List<double> quantities,
     required List<double> prices,
@@ -57,9 +56,9 @@ abstract class CartRepository {
   /// [quantity] - New quantity
   /// [price] - Unit price
   ///
-  /// Returns updated cart item list.
+  /// Returns true if successful.
   /// Throws exceptions on failure.
-  Future<List<CartItem>> updateQuantity({
+  Future<bool> updateQuantity({
     required String itemId,
     required double quantity,
     required double price,