Accent-insensitive search (unaccent/f_unaccent) — Mars leg

Accent-insensitive name/text search (fleet decision bs-mr6s4nyj1th). Shared convention: IMMUTABLE PARALLEL SAFE wrapper f_unaccent(text)=SELECT unaccent('unaccent',$1); search predicates wrap BOTH sides f_unaccent(lower(col)) vs f_unaccent(lower($q)); index per-surface (btree prefix/eq, pg_trgm GIN substring over same expr); ñ folds→n; EMAIL EXCLUDED (canonicalizeEmail owns identity, do NOT touch auth/dedup path). Steps: db inventory Mars search surfaces (which substring→GIN vs prefix→btree, whether unaccent+pg_trgm exist), create f_unaccent + indexes (audit pre-apply DDL), coder wraps predicates. Cross-project pattern (pluto PLUTO-505, venus filing).