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

lib/models/bar_tab.dart

@@ -5,6 +5,7 @@ import 'tab_item.dart';
 class BarTab {
   final String id;
   final String customerName;
+  final String? email;
   final DateTime openedAt;
   final int version;
   final List<TabItem> items;
@@ -12,6 +13,7 @@ class BarTab {
   const BarTab({
     required this.id,
     required this.customerName,
+    this.email,
     required this.openedAt,
     this.version = 0,
     required this.items,
@@ -31,11 +33,19 @@ class BarTab {
       other is BarTab &&
           id == other.id &&
           customerName == other.customerName &&
+          email == other.email &&
           openedAt == other.openedAt &&
           version == other.version &&
           listEquals(items, other.items);
 
   @override
   int get hashCode =>
-      Object.hash(id, customerName, openedAt, version, Object.hashAll(items));
+      Object.hash(
+    id,
+    customerName,
+    email,
+    openedAt,
+    version,
+    Object.hashAll(items),
+  );
 }