Soju User Delete Hash

When deleting a Soju IRC bouncer user, the CLI requires a confirmation token. That token is simply the first 6 hex characters of the SHA-1 hash of the username, computed as `printf <username> | sha1sum | head -c6`. Since it's deterministic and not stored in the database, you can automate the two-step deletion into a single command. A more robust alternative uses command substitution to capture the token from the first invocation and pass it back automatically, guarding against future implementation changes.