Clicking Recalculate in the Commute tab sends a POST to /api/commute with the correct workspace and job id

Prove the pipeline engine's frugality contract end-to-end in a real browser: the enrich stage calls /api/commute through the same-origin worker and a {locked:true} singleflight response does not crash the UI; and concurrent clients on the same workspace do NOT each fire the LLM/Maps calls because compute_lock holds the singleflight, with browsers self-selecting before CF Worker fallback claims.