v0.18.2

• A new computer gets set up with you. When you start a session or
  connect a robot (or run openrua connect, openrua login) and Docker is
  missing, your user may not use it yet, or its service is stopped,
  OpenRUA says why it is needed and offers the fix, showing the commands
  and running them only on a yes. The setup menu itself opens without it. When the agent
  you start a session or connect a robot with is not signed in, it offers
  to sign it in there and then.
• openrua login [agent] signs your coding agent in by running the
  agent's own sign-in inside the sandbox image, so its CLI need not be
  installed on the computer: a link to open in any browser and a code.
  Each agent's manifest names its sign-in (credentials.login). A missing
  login now says run openrua login <agent>; the old hint's
  claude login is no longer a Claude Code command (claude auth login
  is).
• README: Quick start is the path from a bare computer to a robot doing
  something, with details behind links. The CaP-Bench demo walkthrough
  moved to running-experiments.md;
  install.md gains a Docker section and explains the
  agent's login before the images.