GitHub Action should reply in review comment threads

[thomaseude]

When opencode is invoked from a pull_request_review_comment event, it currently responds with a top-level PR comment.

For inline review discussions, it would be useful to optionally reply directly in the triggering review comment thread so the response stays next to the reviewed code and within the existing discussion.

[github-actions]

This issue doesn't fully meet our contributing guidelines.

What needs to be fixed:

• No issue template was used. This appears to be a feature request, but it's missing the required [FEATURE]: prefix in the title and the verification checkbox required by the Feature Request template.

Please edit this issue to address the above within 2 hours, or it will be automatically closed.

If you believe this was flagged incorrectly, please let a maintainer know.

[github-actions]

This issue has been automatically closed because it was not updated to meet our contributing guidelines within the 2-hour window.

Feel free to open a new issue that follows our issue templates.