feat: split add customer optional

lib/presentation/payment/pages/payment_page.dart

@@ -19,11 +19,13 @@ class PaymentPage extends StatefulWidget {
   final Order order;
   final bool isSplit;
   final String? splitType;
+  final String? customerId;
   const PaymentPage({
     super.key,
     required this.order,
     this.isSplit = false,
     this.splitType,
+    this.customerId,
   });
 
   @override
@@ -462,7 +464,7 @@ class _PaymentPageState extends State<PaymentPage> {
     } else {
       final request = PaymentSplitBillRequest(
         amount: widget.order.totalAmount ?? 0,
-        customerId: '',
+        customerId: widget.customerId ?? "",
         items: itemPending
                 ?.map((item) => SplitItem(
                       orderItemId: item.id ?? "",