Fuzzy search

Typo-tolerant identity search over username, first/last name, email and phone, ranked by pg_trgm trigram similarity. Matches when EITHER the similarity operator fires (typo tolerance, governed by pg_trgm.similarity_threshold) OR q is a plain substring of the haystack OR q exactly equals the account's Privy DID. Row visibility is the identical compiled authz filter GET /accounts uses, so this endpoint cannot surface anything the plain list would hide. Like every tenant-bearing list, the search covers the caller's OWN session tenant unless it says otherwise — platform admins included. tenant_id=<another tenant> and all_tenants=true require the cross_tenant grant (403 otherwise); passing both, or a malformed value, is a 400. scoped_to_tenant names the tenant searched (empty with all_tenants=true, which also sets all_tenants). Service accounts are excluded by default; kind=service|all surfaces them for tenant admins.