Allow refreshing sessions to prevent logout on frequently used devices

**Is your feature request related to a problem? Please describe.**
I access authentik or services protected by authentik several times a day. A the end of the day i shut down my desktop PC. Currently this requires me to log in into authentik everytime I reopen my browser. I can use the "stay signed in" feature but in the end it always logs me out when the set timeframe expires.

**Describe the solution you'd like**
Add a "session refresh" feature. This would work as a toggle switch and would reset the session timeout counter to its initial value everytime authentik is accessed. E.g.:
- I login into authentik at 10:00 with the session duration set for 4 hours, meaning i would get logged out at 14:00
- I authenticate with authentik at 13:00 - this would refresh my session counter and move the log out time to 17:00
- repeat until i no longer access authentik within the set session timeframe, logging me out 4 hours after my last interaction.

**Describe alternatives you've considered**
I am not familiar with the technical details, but I am sure this feature is well explored by other apps and there are many best practices in place how to keep the session alive.

**Additional context**
N/A

No files, tests, or entry points are named. Start by locating the session timeout and “stay signed in” behavior described in the issue, then determine how an optional sliding session timeout should interact with authentication access. Done means the toggle refreshes the configured timeout after activity and preserves logout after inactivity, with coverage for those timing cases.

Written by the indexing model from the issue text.