fix(dag): ReviewGateError message hardcodes "deep workflow" for all modes #305

Discovered by live testing on v1.0.21: calling control(complete) on a standard-mode workflow with an unresolved review returns:

Cannot complete deep workflow dag_...: unresolved review outcome(s): decision

The gate behavior is correct; only the wording is wrong — the message should name the actual mode (or omit it). One-line fix in the ReviewGateError constructor message (dag.ts).