Request offline_access so the IdP issues a refresh token, and add an
OAUTH_SCOPES override for providers that reject or extend the default
list. Closes#104
Keycloak rejects an end-session request that carries
post_logout_redirect_uri without id_token_hint or client_id. Store the
id_token from the token exchange in an httpOnly cookie, pass it as
id_token_hint together with client_id on logout, and clear it with the
refresh token.
Fixes#102
Add opt-in SSO authentication alongside Basic Auth. OAuth endpoints are
auto-discovered via .well-known, with support for external IdPs
(Keycloak, Authentik) via configurable OAUTH_ISSUER_URL. Sessions
persist through httpOnly refresh token cookies with automatic renewal.
Matthieu MALVACHE