fix(ci): skip auto-merge step when lockfile is unchanged

The "Enable auto-merge" step runs unconditionally, even when the
lockfile didn't change and no PR exists. This causes the workflow
to fail with "lockfile PR was not found."

Use a step output to gate the auto-merge step so it only runs
when a PR was actually created or updated.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.github/workflows/refresh-lockfile.yml

@@ -51,11 +51,13 @@ jobs:
           fi
 
       - name: Create or update pull request
+        id: upsert-pr
         env:
           GH_TOKEN: ${{ github.token }}
         run: |
           if git diff --quiet -- pnpm-lock.yaml; then
             echo "Lockfile unchanged, nothing to do."
+            echo "pr_created=false" >> "$GITHUB_OUTPUT"
             exit 0
           fi
 
@@ -79,8 +81,10 @@ jobs:
           else
             echo "PR #$existing already exists, branch updated via force push."
           fi
+          echo "pr_created=true" >> "$GITHUB_OUTPUT"
 
       - name: Enable auto-merge for lockfile PR
+        if: steps.upsert-pr.outputs.pr_created == 'true'
         env:
           GH_TOKEN: ${{ github.token }}
         run: |