The pair-code flow always called startTeslaConnect() afterwards, which
redirected the car browser to auth.tesla.com even when the server already
held tokens from the desktop OAuth. Now connectIfNeeded() re-fetches
status post-login and short-circuits when connected: true. The car flow
becomes: enter 6-digit code → 'Tesla connected · Carried over from your
other device — ready to go.' No second OAuth.
