users(cassie): add ssh for backup

Changed files
+6
users
cassie
home
dev
+6
users/cassie/home/dev/ssh.nix
···
hostname = "github.com";
user = "git";
};
+
+
backup = {
+
hostname = "koumakan";
+
user = "forgejo";
+
identityFile = "~/.ssh/id_minecraft_backup";
+
};
};
# extraConfig is config for the Host * block.