Add agent templates section to README

[mergisi]

Summary

• Added an "Agent Templates" section to the README pointing to 190+ ready-made agent configurations
• Templates cover roles like Project Manager, Software Engineer, DevOps, QA, Security, and more
• Compatible with JavaClaw's skill system

Small addition that helps new users find pre-built agent configurations to get started faster.

[cla-bot]

We require contributors to sign our Contributor License Agreement, and we don't have @mergisi on file. In order for us to review and merge your code, please create a PR where you add yourself to the contributors of JobRunr. This only needs to be done once. As soon as that is done, we can review your PR.

Thanks a lot!

[mergisi]

Hi! I've submitted the CLA PR at jobrunr/clabot-config#79. The CLA bot seems to also require CLA for the CLA config repo itself, so it might need manual approval. Happy to wait. Thanks!