-- pg_turbovec v2.8.4
--
-- Code-only release. No SQL surface change, no wire-format change
-- (MetaPageData::version stays 8). `ALTER EXTENSION pg_turbovec UPDATE`
-- is sufficient; no REINDEX.
--
-- 1. Phase Z1: an ordinary (TurboQuant) IVF index whose deferred-commit
--    flush rewrites the relfile now PRESERVES `lists` and stamps
--    `ivf_degraded`, so `turbovec.index_is_degraded()` and the throttled
--    `ambeginscan` WARNING report the degradation instead of the IVF
--    identity being silently erased. Both are existing v4 meta fields.
-- 2. An INSERT into an index built WITH (assign_dups > 1) is rejected with
--    FEATURE_NOT_SUPPORTED naming `assign_dups`, instead of claiming
--    "corrupt relfile pages" about a healthy index.