GitHub Copilot app for Beginners: Using the diff, terminal, and browser

The GitHub Copilot app adds three built-in panels — diff, terminal, and browser — so you can review agent code changes, run commands, and preview results without leaving the app. The diff panel highlights added and removed lines in green and red, letting you accept changes, leave comments, or ask Copilot to revise; the terminal panel supports running scripts like npm run dev with multiple windows; and the browser panel uses the Pick & Polish tool to select elements for the agent to adjust.