Agentic deploy

The first time a project runs, an agent works out how to run it: what the services are, what commands start them, what ports they bind, what environment they need. It writes that into the project's configuration and boots the sandbox. When it needs an answer it pauses in awaiting_user, and the deploy continues once you reply. Deploys also happen on their own after a push to the default branch, and to recover a failed environment.