feat: New Open Tab dialog with search and optional customer email. Drinks are now grouped per order. Payments trigger cha-ching and money rain.

test/tab_events_test.dart

@@ -694,6 +694,7 @@ void main() {
       productName: 'Cola',
       unitPriceInCents: 250,
       quantity: 2,
+      orderId: 'order-1',
     );
 
     expect(event.payload['occurredAt'], '2026-10-24T21:41:03.120Z');
@@ -723,6 +724,7 @@ class _FixedIdEventFactory extends TabEventFactory {
     required String productName,
     required int unitPriceInCents,
     required int quantity,
+    required String? orderId,
   }) {
     final event = super.lineAdded(
       tabId: tabId,
@@ -732,6 +734,7 @@ class _FixedIdEventFactory extends TabEventFactory {
       productName: productName,
       unitPriceInCents: unitPriceInCents,
       quantity: quantity,
+      orderId: orderId,
     );
     return TabEvent(id: 'fixed', payload: {...event.payload, 'id': 'fixed'});
   }