Contracts and Implementation build into two separate bin/ folders, so
there's nowhere valid to point --plugins at without a staging step first
— every manual verification this session has done that staging by hand.
stage-plugins.sh does it for every plugin in one pass; run-sample.sh
stages then runs samples/WindowDemo windowed, forwarding extra args to
`engine run` (e.g. --screenshot).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N1qPfzq8TDCUMFMV3UwV5N
