[UX] improve state management

[oteku]

Whenever you display a Safe, next time you go to tzsafe.marigold.dev, you access last wallet you accessed. It is disturbing cause it can be a safe you are not in (you displayed a random wallet, or you connect with multiple accpount to the app.

Expected behavior: tzsafe.marigold.dev routes to the first wallet in you imported wallet list or to new wallet page if you have none.

⚠️ test with multiple account using the same browser

[quentin-burg]

Closed with #172