Why: Checklist B6 needs a repeatable database-only baseline that cannot reach production ports or instances. Evidence: run_pgbench.sh --self-check passed (help, unknown arg, foreign name, busy port, SIGINT cleanup). Timed runs are recorded separately. Impact: New load-test entry and README note. No product or release-gate change. Refs: docs/release-multi-instance.md B6 Co-authored-by: Cursor <cursoragent@cursor.com>