Teach the kanban reviewer to vary its inspection lens per review round
instead of repeating the same framing: round 1 reads the artifact cold
before the implementer narrative, round 2 checks out and empirically
executes the work, round 3+ audits strictly against the original
acceptance criteria and every prior request_changes item. The round is
derived from the changes_requested entries already visible in the
reviewer's worker context (live-verified against build_worker_context
across two real request_review/request_changes rounds on an isolated
board). Also adds a lens-variation note for parallel delegate_task
review fan-outs. Contract test updated with section order and lens
assertions.
