The stepwise-coding IR had no workflow-step seam node, so a per-task
enabledWorkflowSteps entry (e.g. browser verification) would never execute.
Add the seam node on the success path (steps -> workflow-step -> review,
once post-foreach) and declare browser-verification as an optional step,
matching the coding workflow. Covers the dead-toggle gap with resolver and
engine execution-divergence tests.