If you delete a wallet without deleteing the cards first the cards are orphaned.
- Create a wallet.
- Enable Boltcards extension
- Create a Card UID=12345671234567
- Delete the wallet
That UID cannot be used on that server again.
Also the card cannot be deleted using the api leaving no easy way out.

Shouldnt the column "wallet" in the "cards"-table be a FOREIGN KEY with CASCADE DELETE?
