fix(ci): check out PR branch for mention bot so commits land on the PR

.github/workflows/claude-bot.yml

@@ -419,6 +419,11 @@ jobs:
       - uses: actions/checkout@v7
         with:
           fetch-depth: 0
+      - name: Check out the PR branch when the comment is on a pull request
+        if: github.event.issue.pull_request
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: gh pr checkout ${{ github.event.issue.number }}
       - uses: anthropics/claude-code-action@v1
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}