feat(harness): add verdict prefix to reviewer comments (#1153)

* feat(harness): add verdict prefix requirement to reviewer system prompt

The PR reviewer agent now must begin every comment with APPROVED,
APPROVED WITH MINOR COMMENTS, or REQUESTING CHANGES so outcomes
are immediately visible and parseable.

* feat(harness): use gh pr review for formal review verdicts

Instead of plain comments with text prefixes, the reviewer agent now
submits formal GitHub PR reviews via `gh pr review` with --approve,
--request-changes, or --comment. This integrates with branch protection
rules and makes the review status machine-readable.

* refactor(harness): move review verdict to review.md as one-liner

Keep system.md as pure workspace context. The review task prompt now
ends with a single directive to submit a formal PR review rather than
a plain comment.

* Update PR review submission instructions

Clarified instructions for submitting PR reviews.

Author: aidandaly24

.github/harness/prompts/review.md

@@ -14,5 +14,4 @@ Review the PR. If there are any serious issues that require code changes before
 each issue explaining the problem. If there are multiple ways to fix an issue, list the options so the author can
 choose. Skip style nits and minor suggestions — only flag things that actually need to change.
 
-If all serious issues have already been raised in existing comments, or if you found no new issues, post a single
-comment on the PR saying it looks good to merge (or that all issues have already been flagged).
+When finished, submit a formal PR review (approve or request changes) with individual and inline comments in it. Be specific with line numbers.