Replace the pre-merge `workflow-step` seam node + `optionalSteps` declaration in
the coding and stepwise-coding built-ins with a `browser-verification`
optional-group (default OFF) whose template runs the browser-verification step.
Enabled tasks run it once pre-merge; disabled tasks bypass it (two-task
divergence engine test; stepwise confirmed run-once post-foreach). Coding is now
interpreter-deferred like stepwise (the group is a branching node). Parity
oracles updated deliberately. Legacy seam-anchor/runWorkflowSteps left for U7.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
5506fcc0fc