RhinoFrame private beta package.

Target: Rhino 8 for macOS.

No environment variables are required for beta testers. This package opens the
hosted RhinoFrame app by default:

https://rhinoframe.howtorhino.com/

RHINOFRAME_WEB_URL is only a developer override for pointing the panel at a
local Vite dev server. Do not set RHINOFRAME_DEV_AUTH_TOKEN for external beta
testers.
