a4588a57cb
- Add UserSession and QRLoginChallenge models for session tracking and mobile QR authentication - Add session_manager utility with create/validate/revoke/cleanup functions and QR challenge helpers - Add /api/sessions endpoints for listing, revoking, and 'log off everywhere' functionality - Add /api/qr-auth endpoints for challenge creation, polling, and claiming with API token issuance - Add session config fields (lifetime, custom override, QR TTL) - Update get_current_user to validate server-side sessions - Create server-side sessions on all login paths (local, OAuth, social, admin) - Revoke server-side session on logout - Configure SessionMiddleware max_age from session lifetime settings - Graceful degradation: old sessions without _session_token continue to work Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>