0.4.9

What's Changed\n- Prevent the runWorkflow plugin from starting a second workflow when the latest session message already contains an active workflow tool call.\n- Add tests covering the allowed single-workflow path and the rejected concurrent-workflow path.\n- Update the upgrade checklist to verify the latest-message lookup and concurrency guard behavior.\n\n## Verification\n- npm test\n- npm run build\n- npm publish (via release helper)