Add RunLedger replay gate for agent regressions

[ZackMitchell910]

Summary

• add a replay-only RunLedger eval suite (suite/case/schema/cassette + stub agent)
• add a baseline file for regression gating
• add a GitHub Actions workflow using runledger/Runledger@v0.1
• add a small README note + ignore runledger_out/

How to run locally

runledger run evals/runledger --mode replay --baseline baselines/runledger-demo.json

Notes

• no external calls; replay-only cassette
• feel free to remove the suite/workflow if it is not desired
• GitHub Actions note: workflows from first-time contributors/forks may require a maintainer to click “Approve and run” before checks will execute.

[vercel]

@ZackMitchell910 is attempting to deploy a commit to the zeeland's projects Team on Vercel.

A member of the Team first needs to authorize it.

[github-actions]

Hello @ZackMitchell910, thanks for opening your first pull request 😊! We really appreciate your work. Happy Coding 🎉🎊 !