getById method
Returns the row with the given id, or null if it does not exist.
Soft-deleted rows are returned (inspect deleted_at to detect).
Implementation
@override
Future<Map<String, dynamic>?> getById(String table, String id) async {
final row = _tables[table]?[id];
if (row == null) return null;
return Map<String, dynamic>.from(row);
}