Reduce session expiry from 30 days to 7 days of inactivity while
preserving a 30-day absolute token lifetime for itsdangerous:
- SESSION_MAX_AGE_DAYS=7: sliding window for DB expires_at + cookie
- SESSION_TOKEN_HARD_CEILING_DAYS=30: itsdangerous max_age (prevents
rejecting renewed tokens whose creation timestamp exceeds 7 days)
- get_current_user: silently extends expires_at and re-issues cookie
when >1 day has elapsed since last renewal
- Active users never notice; 7 days of inactivity forces re-login;
30-day absolute ceiling forces re-login regardless of activity
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>