Session tokens now carry an :exp claim anchored to created-at (not
modified-at), so activity cannot extend the session beyond the
absolute maximum (default 30 days, configurable via
PENPOT_AUTH_TOKEN_COOKIE_MAX_AGE_ABSOLUTE). The existing token
verification already rejects expired tokens, so enforcement is
automatic. Also extends the GC task to purge expired
http_session_v2 rows, which were previously never cleaned up.
Closes#11444
AI-assisted-by: longcat-2.0
d6e82f44a6