Develop a simple cockpit-like application built on a secure frame model, as a proof of concept for how we might do this in Cockpit. The goal would be to have a simple application build with a toplevel frame that's capable of logging in via websocket and routing messages between security-isolated frames.

If successful, this would become the technical underpinnings of the next major technological development in Cockpit, along with solving a longstanding and extremely visible security issue (no isolation between separate hosts in a Cockpit session —- every host can execute arbitrary code on every other host).