update cart/favorite

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

@@ -25,6 +25,7 @@ abstract class CartRepository {
   /// [itemIds] - Product ERPNext item codes
   /// [quantities] - Quantities for each item
   /// [prices] - Unit prices for each item
+  /// [conversionFactors] - Conversion factors (m² to tiles) for each item
   ///
   /// Returns true if successful.
   /// Throws exceptions on failure.
@@ -32,6 +33,7 @@ abstract class CartRepository {
     required List<String> itemIds,
     required List<double> quantities,
     required List<double> prices,
+    List<double?>? conversionFactors,
   });
 
   /// Remove items from cart
@@ -55,6 +57,7 @@ abstract class CartRepository {
   /// [itemId] - Product ERPNext item code
   /// [quantity] - New quantity
   /// [price] - Unit price
+  /// [conversionFactor] - Conversion factor (m² to tiles)
   ///
   /// Returns true if successful.
   /// Throws exceptions on failure.
@@ -62,6 +65,7 @@ abstract class CartRepository {
     required String itemId,
     required double quantity,
     required double price,
+    double? conversionFactor,
   });
 
   /// Clear all items from cart