A hosted agent whose Nous bootstrap session dies terminally (invalid_grant /
quarantine) looks HEALTHY to every liveness/connectivity probe — the machine,
relay ws, and dashboard all stay up — yet every inference turn hard-fails with
a provider-auth error until a human re-logs-in. Nothing currently surfaces that
condition to NAS.
Add get_nous_session_validity() (valid|terminal|unknown), classified from local
auth-store state (no working token required), and report it on the public
/api/status payload. NAS's 2-min health sweep reads it and re-mints the
bootstrap session in place on 'terminal'.
Anti-flap: only a terminal failure (relogin_required / persisted quarantine
marker with tokens cleared) maps to 'terminal'; transient/mid-rotation blips and
merely-expiring tokens report 'unknown' so a healthy box never triggers a
spurious re-mint.
Part of the hosted-agent bootstrap-session self-heal (NAS side reads this field).
