Get current user and org info

The caller and their org. user is the CALLER's own row (auth["user_id"]), never the org's first user — or, for a SERVICE key (a machine principal with no users row), a description of that principal: id is the key's id, name its label, email the actor identity the audit log records for it, role its pinned viewer. Other credentials not bound to a member (device licenses, IdP principals) get 404 user_not_found.