Run the L1/L2 agent-review ladder across multiple open PRs concurrently instead of serially. Triggers when 2+ open PRs each need /l1-review and /l2-review before human review. Dispatches one delegated review agent per PR (each runs /l1-review then /l2-review sequentially, reading the posted L0 /review marker as evidence), collects verdicts, routes clean vs needs-work. Does not itself run /review, /l1-review, or /l2-review.
