Implement retention time for door logins

When door is unlocked we store the door login action. Right now (I believe) this is stored essentially forever. This should be removed after a certain time, for example 30 days.

It could be useful for statistical reasons to preserve how many logins happened per week/month (anonymized/aggregated).

Jeg trur norsk lov sier at det skal slettes etter 90 dager. Datatilsynet vil nok være behjelpelig hvis det er noen som lurer.