feat: make server owner of tabs

lib/database/app_database.dart

@@ -162,6 +162,9 @@ class RemoteSyncState extends Table {
 
   TextColumn get serverCursor => text().nullable()();
 
+  /// Where the feed of settlements made anywhere in the venue left off.
+  TextColumn get settlementsCursor => text().nullable()();
+
   DateTimeColumn get lastSuccessfulSyncAt => dateTime().nullable()();
 
   DateTimeColumn get lastAttemptedSyncAt => dateTime().nullable()();
@@ -204,6 +207,26 @@ class TabEvents extends Table {
   Set<Column> get primaryKey => {id};
 }
 
+/// Outcomes of the stock adjustments sent by the dashboard, waiting to be
+/// reported. A row also records that its adjustment was handled, so it is
+/// kept for a while after the server acknowledges it: the same adjustment
+/// can still arrive in a response computed before the server saw the outcome.
+@DataClassName('StockAdjustmentResultRow')
+class StockAdjustmentResults extends Table {
+  /// The adjustment's id from the server.
+  TextColumn get id => text()();
+
+  /// The outcome as JSON, exactly as it is sent.
+  TextColumn get payload => text()();
+
+  BoolColumn get acknowledged => boolean().withDefault(const Constant(false))();
+
+  DateTimeColumn get createdAt => dateTime()();
+
+  @override
+  Set<Column> get primaryKey => {id};
+}
+
 @DriftDatabase(
   tables: [
     Products,
@@ -216,13 +239,14 @@ class TabEvents extends Table {
     RemoteSyncState,
     ProcessedRemoteCommands,
     TabEvents,
+    StockAdjustmentResults,
   ],
 )
 class AppDatabase extends _$AppDatabase {
   AppDatabase([QueryExecutor? executor]) : super(executor ?? _openConnection());
 
   @override
-  int get schemaVersion => 15;
+  int get schemaVersion => 17;
 
   @override
   MigrationStrategy get migration {
@@ -325,6 +349,19 @@ class AppDatabase extends _$AppDatabase {
         if (from < 15) {
           await migrator.createTable(tabEvents);
         }
+
+        if (from < 16) {
+          await migrator.createTable(stockAdjustmentResults);
+        }
+
+        if (from < 17 &&
+            await hasTableColumn('remote_sync_state', 'device_id') &&
+            !await hasTableColumn('remote_sync_state', 'settlements_cursor')) {
+          await migrator.addColumn(
+            remoteSyncState,
+            remoteSyncState.settlementsCursor,
+          );
+        }
       },
     );
   }