[Suggestion] Optional Chat Expiry time

[shiribailem]

This is more a thing for different usage scenarios. It would be nice to have a setting option to automatically "expire" chats and a setting to default to new chats.

I don't really save conversations, I'm often starting my usage of BigAGI by deleting whatever the last chat was. So it would be nice for me to just start on a blank window and maybe save the old conversation in history if I need it, with it "expiring" (ie. auto-deleting) after a day or two.