-- 0017_users_extensions.sql
--
-- Add the columns the user-management UI needs:
--   email                 — optional, free-form text; format-checked
--                           in Go on insert/update via net/mail.ParseAddress
--   disabled_at           — soft-delete tombstone. NULL = enabled
--   must_change_password  — flag set by admin-create + setup-token flow;
--                           cleared by /setup or /settings/account
--
-- Plus a case-insensitive unique index so 'Alice' and 'alice' can't
-- both exist (lowercase normalisation is applied in the Go layer
-- on every CreateUser; this index defends the invariant).
--
-- Column-level ALTERs (CLAUDE.md prefers these over rebuilds; safe
-- under foreign_keys=ON).

ALTER TABLE users ADD COLUMN email TEXT;
ALTER TABLE users ADD COLUMN disabled_at TEXT;
ALTER TABLE users ADD COLUMN must_change_password INTEGER NOT NULL DEFAULT 0;

CREATE UNIQUE INDEX users_username_lower ON users(LOWER(username));