find method
Returns the formula spec with id, or null.
Implementation
@override
Future<FormulaSpec?> find(FormulaId id) async {
final rows = db.select('SELECT data FROM formulas WHERE id = ?', [
id.value,
]);
if (rows.isEmpty) return null;
return FormulaSpec.fromJson(
jsonDecode(rows.first['data'] as String) as Map<String, dynamic>,
);
}