feat: add Raven's Verdict PR review tool (#1054)

* feat: add Raven's Verdict PR review tool

* docs: add usage guidance to Raven's Verdict README

* docs: add guidance to skip PRs that shouldn't merge

tools/maintainer/review-pr-README.md

@@ -0,0 +1,55 @@
+# Raven's Verdict - Deep PR Review Tool
+
+Adversarial code review for GitHub PRs. Works with any LLM agent.
+
+> **Status: Experimental.** We're still figuring out how to use this effectively. Expect the workflow to evolve.
+
+## How It Works
+
+Point your agent at `review-pr.md` and ask it to review a specific PR:
+
+> "Read tools/maintainer/review-pr.md and apply it to PR #123"
+
+The tool will:
+
+1. Check out the PR branch locally
+2. Run an adversarial review (find at least 5 issues)
+3. Transform findings into professional tone
+4. Preview the review and ask before posting
+
+See `review-pr.md` for full prompt structure, severity ratings, and sandboxing rules.
+
+## When to Use
+
+**Good candidates:**
+
+- PRs with meaningful logic changes
+- Refactors touching multiple files
+- New features or architectural changes
+
+**Skip it for:**
+
+- Trivial PRs (typo fixes, version bumps, single-line changes)
+- PRs you've already reviewed manually
+- PRs where you haven't agreed on the approach yet — fix the direction before the implementation
+
+## Workflow Tips
+
+**Always review before posting.** The preview step exists for a reason:
+
+- **[y] Yes** — Post as-is (only if you're confident)
+- **[e] Edit** — Modify findings before posting
+- **[s] Save only** — Write to file, don't post
+
+The save option is useful when you want to:
+
+- Hand-edit the review before posting
+- Use the findings as input for a second opinion ("Hey Claude, here's what Raven found — what do you think?")
+- Cherry-pick specific findings
+
+**Trust but verify.** LLM reviews can miss context or flag non-issues. Skim the findings before they hit the PR.
+
+## Prerequisites
+
+- `gh` CLI installed and authenticated (`gh auth status`)
+- Any LLM agent capable of running bash commands