Dead-lettered records per table for the tenant engine

Records this project's engine ACCEPTED (ingest answered 200) and then could not insert — a type ClickHouse refused, an unparseable timestamp, an unreadable envelope. They are parked per table and are not in any table, so no query finds them and no ingest response reported them. Read live from the engine's admin-only GET /v1/ops/dlq/stats with the operator key the API injects server-side; the count is the depth NOW, and tables omits the tables holding none. Read-only; any org member. Nothing here replays or discards a record: the engine exposes no route that can, so the repair is to fix the value and ingest it again.