feat: add historical data

lib/database/app_database.dart

@@ -187,6 +187,23 @@ class ProcessedRemoteCommands extends Table {
   Set<Column> get primaryKey => {commandId};
 }
 
+/// Outbox of tab events (lines added/removed, settlements) waiting to be
+/// sent to the server for sales statistics. Rows are deleted once the server
+/// acknowledges or rejects them.
+@DataClassName('TabEventRow')
+class TabEvents extends Table {
+  /// The event's UUID.
+  TextColumn get id => text()();
+
+  /// The event as JSON, exactly as it is sent.
+  TextColumn get payload => text()();
+
+  DateTimeColumn get createdAt => dateTime()();
+
+  @override
+  Set<Column> get primaryKey => {id};
+}
+
 @DriftDatabase(
   tables: [
     Products,
@@ -198,13 +215,14 @@ class ProcessedRemoteCommands extends Table {
     AppSettingsTable,
     RemoteSyncState,
     ProcessedRemoteCommands,
+    TabEvents,
   ],
 )
 class AppDatabase extends _$AppDatabase {
   AppDatabase([QueryExecutor? executor]) : super(executor ?? _openConnection());
 
   @override
-  int get schemaVersion => 14;
+  int get schemaVersion => 15;
 
   @override
   MigrationStrategy get migration {
@@ -303,6 +321,10 @@ class AppDatabase extends _$AppDatabase {
         if (from < 14 && !await hasTableColumn('products', 'infinite_stock')) {
           await migrator.addColumn(products, products.infiniteStock);
         }
+
+        if (from < 15) {
+          await migrator.createTable(tabEvents);
+        }
       },
     );
   }