bug(base): session expires unexpectedly during active use

[ralflang]

Summary

Sessions time out with "session expired" message while the user is actively working in the Horde 6 web interface. This happens intermittently, not on every session.

Reproduction

1. Log in to Horde 6 web interface
2. Work normally (navigate, create items, etc.)
3. Intermittently, "session expired" message appears despite active use

Environment

• Horde 6 (current FRAMEWORK_6_0)

Reported by: Ruud (via direct message)