isLoggedIn trusted id and role straight from the JWT and never
re-checked the database, so a demoted admin kept their old role and a
deleted user kept a working session until the token expired (up to
JWT_EXPIRES_IN). This also undercut the "last admin" guards.
isLoggedIn now loads the user from the DB by the token's id on every
request: a missing user returns 401 (deleted), and req.user carries the
fresh DB row so the current role is always used downstream.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
