AnchorRecomputationWorker

Anchor recomputation batch transport (worker only).

📄️Run one recomputation batch (worker only)

Claims the next batch of members after the run's cursor, recomputes each, advances the cursor under compare-and-set and enqueues the next batch. Idempotent under redelivery: a duplicate loses the compare-and-set and writes nothing, and a task whose batchIndex no longer matches the run is stale and does nothing at all. 204 consumes the task, anything else holds it for redelivery.