Mirror the public-link convenience Studio already has for its own UI, for
JupyterLab. Off by default; opt in two ways:
docker run -e UNSLOTH_JUPYTER_CLOUDFLARE=1 ... unsloth/unsloth
docker exec <container> unsloth-jupyter-tunnel --force
unsloth-jupyter-tunnel waits for JupyterLab, reuses a cached cloudflared (or
fetches the static binary for the arch, no account needed), and starts a
quick tunnel to the Jupyter port; the https://<name>.trycloudflare.com URL is
printed to docker logs. supervisord runs it as the jupyter-cloudflare program,
autostarted only when UNSLOTH_JUPYTER_CLOUDFLARE=1 (studio_launch.sh exports a
0 default so the autostart gate expands, matching the sshd pattern). JupyterLab
still enforces its password, so the tunnel is not an open door.
Verified: the helper fetches cloudflared and mints a working trycloudflare URL
that reaches JupyterLab (HTTP 200) inside a running container.