A post-release error timestamp does not by itself make the release causal: join runtime logs

A post-release error timestamp does not by itself make the release causal: join runtime logs to the exact deployed SHA, then join background-work failures to each record's creation time. This distinguishes new work introduced after cutover from old work merely retried or finalized by the new process. The method is strongest for durable queues with created/attempted/processed timestamps; it cannot rule out behavioral regressions when traffic is absent or job provenance is incomplete.