-- Drop NOT NULL on deadlines.user_id.
--
-- The multi-tenant company refactor (20260330130000) moved deadlines to
-- company ownership: company_id column + company-scoped RLS, and the tax
-- deadline generator (lib/tax/deadline-generator.ts) stopped sending user_id.
-- The refactor dropped NOT NULL on user_id for audit_log and company_settings
-- (and later fiscal_periods, narrative_signatures) but missed deadlines —
-- since then every auto-generation insert fails with 23502, and because the
-- generator deletes existing system deadlines before inserting, affected
-- companies lost their tax deadlines entirely.
--
-- user_id stays as an optional "created by" attribution for manually created
-- deadlines (app/api/deadlines/route.ts still sends it). Ownership is
-- company_id.
ALTER TABLE public.deadlines ALTER COLUMN user_id DROP NOT NULL;