agents(review-code): prompt to post PR comments with agent signature (#4246)

When reviewing an existing pull request, the `review-code` skill only
produced a local artifact and lacked instructions for posting review
comments back to GitHub or distinguishing agent-generated comments from
human reviews.

Update the `review-code` skill to ask the user whether to post comments
when reviewing a PR, and require an italicized note at the end of each
posted comment identifying it as agent-generated with a magnanimous
title.

.agents/skills/review-code/SKILL.md

diff --git a/.agents/skills/review-code/SKILL.md b/.agents/skills/review-code/SKILL.md
index 38f7bbb..7589752 100644
--- a/.agents/skills/review-code/SKILL.md
+++ b/.agents/skills/review-code/SKILL.md
@@ -76,4 +76,8 @@
 - Once all sub-agents finish, finalize `code-review-results.md` and provide a
   concise summary with the overall verdict and a clickable markdown link to
   `code-review-results.md` in the response.
-
+- If a PR is being reviewed, ask the user if they want to post comments to the
+  PR.
+- When posting comments to the PR, add a note in italics at the end of each
+  comment identifying it as an agent-generated comment and referring to yourself
+  using a magnanimous title.