Sign in a machine

Every machine signs in with a device code, so a headless server needs neither a browser nor your Google password.

1. Run justdrive login on the machine. Add --name vps-2 to name it.
2. The terminal prints an approval link and a code like HJKL-MNPQ.
3. Open the link in any browser, sign in to your justdrive account, and type the code.
4. Approve the machine. The terminal confirms the sign-in.

The code is good for 10 minutes, and the CLI checks every 5 seconds while it waits. Approving gives that machine its own token, which you can revoke at any time.