Track last time a session was open in the session_store

### Describe the feature or problem you'd like to solve

Computer restarts and I need to restore my sessions. Love to review the sessions that were open to recover them.

### Proposed solution

Add a last_open column of type time to session store. Every 5 minutes, update the time in the column. Then I can see when each session was open regardless of whether I took any action in it.

### Example prompts or workflows

show me all the sessions that were open today
show me all the sessions that were open last week
look at all the open sessions from today - is any of them related to feature X?

### Additional context

_No response_

El issue menciona el session_store, pero no indica rutas de archivos ni de tests. Empieza localizando ese store y el punto de entrada del ciclo de vida de las sesiones; después, inspecciona cómo se persisten y consultan las sesiones tras un reinicio. Se considera terminado cuando se registra periódicamente la hora de la última apertura y se admiten con tests los workflows de sesiones indicados para hoy y la última semana.

Escrito por el modelo de indexación a partir del texto del issue.