Remote control CLI sessions on web and mobile in public preview

GitHub is launching `copilot --remote`, a public preview feature that lets developers monitor and control a running Copilot CLI session from GitHub on the web or via GitHub Mobile apps. The CLI streams session activity in real time, displaying a link and QR code to connect from another device. Remote sessions support all standard Copilot CLI features including mid-session steering, plan review and modification, mode switching, permission approvals, and responding to agent questions. Getting started requires updating to the latest CLI version and running `copilot --remote`. Copilot Business and Enterprise users need an admin to enable the feature first.