Lock screen

I often need to lend a computer to a colleague for a moment and quickly log out of my account. Allow me to set a session lock. Show the active logged in user and allow to enter the password directly to open access.

It will also automatically switch the user to lock mode if they have not been active for more than 3 days.

Start by tracing the existing user and session handling in the administration interface; the issue names no files, entry points, or tests. Clarify how manual locking, password-based unlocking, active-user display, and the three-day inactivity rule should behave, then identify tests that can verify each completed behavior.

Written by the indexing model from the issue text.