You can now restore wallet backups in cashu.me thanks to @moonsettler 's PR
The backup can be restored in the welcome page when you first open the wallet (with a fresh state only). You can also drag&drop the backup file in there.
Beware: this is a stateful backup (after every transaction)! We're also working on a single-seed backup from which your ecash can be restored with the help of the mint.
