-- pg_turbovec 2.6.0 -> 2.7.0
-- IVF + 1-bit sign-BQ composition (WITH (lists = N, bit_width = 1)), a
-- wide-word Hamming kernel (~4.4x), and two BQ insert bugs fixed
-- (tombstone resurrection after VACUUM; duplicate slot on re-insert).
-- Code-only: no wire change (v8), no SQL surface change, no REINDEX.
-- Intentionally empty but MUST exist so ALTER EXTENSION ... UPDATE succeeds.