When the tunnel was started before parseReadiness flipped to URL-required
(or by an external invocation), the manager's status URL stays null and
buildRemoteLoginUrlForTokenType used to fall back to a constructed
http://<configured-hostname>:<port> URL — which the user saw encoded
into the QR as e.g. "fusionstudio:4040".
Add a tailscale status --json fallback that recovers the public tailnet
DNS name and reconstructs the funnel URL (https://<machine>.<tailnet>.ts.net/).
If both sources fail, surface REMOTE_URL_NOT_READY rather than emitting a
non-public URL into the auth/QR payload.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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