feat: persist workflow controls and settle stopped branches

internal/storage/mysql/workflow_signal_source.go

@@ -119,7 +119,7 @@ func selectedWorkflowSignal(ctx context.Context, tx *sql.Tx, g *workflowGraph, r
 		if w.state != "WAITING" {
 			return nil, nil
 		}
-		err := tx.QueryRowContext(ctx, `SELECT id FROM weave_signals WHERE namespace_id=? AND workflow_id=? AND target_step_key=? AND target_activation_sequence=? AND state='PENDING' AND type=? AND payload_version=? AND correlation_key=? AND accepted_at<? ORDER BY accepted_at,id LIMIT 1 FOR UPDATE`, g.view.NamespaceID, g.view.ID, row.view.Key, w.sequence, w.contract.Name, w.contract.PayloadVersion, []byte(w.correlation), w.deadline).Scan(&id)
+		err := tx.QueryRowContext(ctx, `SELECT id FROM weave_signals WHERE namespace_id=? AND workflow_id=? AND target_step_key=? AND target_activation_sequence=? AND state='PENDING' AND type=? AND payload_version=? AND correlation_key=? AND accepted_at<? AND (? IS NULL OR accepted_at<=?) ORDER BY accepted_at,id LIMIT 1 FOR UPDATE`, g.view.NamespaceID, g.view.ID, row.view.Key, w.sequence, w.contract.Name, w.contract.PayloadVersion, []byte(w.correlation), w.deadline, g.view.StopRequestedAt, g.view.StopRequestedAt).Scan(&id)
 		if errors.Is(err, sql.ErrNoRows) {
 			return nil, nil
 		}