When jwt.decode raises InvalidTokenError, decode the token a second time
without signature verification (safe — we never trust the values, just
display them) and append the actual iss/aud claims plus our configured
expected values to the error message. Lets operators see config drift
between HERMES_DASHBOARD_PORTAL_URL / HERMES_DASHBOARD_OAUTH_CLIENT_ID
and what Portal is actually emitting without having to hand-decode the
JWT from the browser cookie.