Add safe outputs for replying to and resolving pull request review comments

[strawgate]

Reply to a PR review comment -- an agent responds to an existing review thread (e.g. answering a reviewer's question, explaining a decision)

Resolve a PR review comment -- an agent marks a review conversation as resolved

This way you can have an Agent run a PR review and then another agent incorporate feedback, etc while tracking the back and forth through standard github pull request comment mechanisms

[strawgate]

i can take a stab at this

[pelikhan]

Slurp our agents.md

[pelikhan]

2 PR best.

[strawgate]

first PR is merged, adding review comment resolution #15668