docs: add Greptile OSS badge to README badge row

[Copilot]

Adds the Greptile for Open Source badge to the README’s centered badge row, where markdown is not rendered. The badge is inserted in HTML form immediately after the existing build-status badge to preserve rendering and layout consistency.

• README badge row

  • Updated /README.md inside the <p align="center"> badge block.
  • Appended a new Greptile badge anchor/image pair after the Actions build-status badge.

• Rendering compatibility

  • Used HTML badge markup (not markdown image-link syntax) so the badge renders correctly within the raw HTML block.

<a href="https://www.greptile.com/?utm_source=oss_badge&utm_medium=readme&utm_campaign=greptile_for_open_source">
  <img alt="Greptile: The War on Bugs" src="https://www.greptile.com/badge.svg" />
</a>

• Fixes docs: add the Greptile for Open Source badge to the README #782

[changeset-bot]

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Latest commit: 5fd5176

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[greptile-apps]

Confidence Score: 5/5

The PR appears safe to merge with no actionable issues identified.

Summary

Adds a linked Greptile for Open Source badge immediately after the build-status badge in the README’s centered HTML badge row.

• Uses HTML markup consistent with the surrounding badges.
• Preserves the existing badge-row structure and layout.

_{Reviews (1) · Last reviewed commit: "docs: add Greptile open source badge to ..."}