Get current session identity

Returns the authenticated user, session capabilities, and normalized clientIp only. Active PostgreSQL sessions renew when 30 days or less remain, to 35 days, at most once per five days. Only the successful cookie-authenticated response that renewed the session reissues the same session cookie and already-present CSRF cookie with the renewed PostgreSQL expiry, without rotating either value; a request carrying x-eurobase-session-renewal: defer never renews. Bearer callers and failed responses receive no browser cookies. Infrastructure, database, network, or process failures are request failures only; they are not logout semantics and do not clear browser auth cookies.