Lägger docs/production-readiness.md och siax/production-gaps.json enligt SIAX Master Definition of Done. Underlag: git-, kod- och live-evidens 2026-11-11. Nivån är evidensbaserad, inte ett leveransgodkännande.
A client retry with the same idempotency key replayed the journal and got
'outcome_unknown' even when the first upload had succeeded, because the
verified DOC0 receipt was never persisted. Store document/version/checksum/
stage on the attempt (sql/021) and return it on replay; only a missing receipt
falls back to observation. No second POST, no duplicate document.