ci: clarify fail-fast lockfile refresh behavior

.github/workflows/refresh-lockfile.yml

@@ -57,7 +57,11 @@ jobs:
           git config user.email "lockfile-bot@users.noreply.github.com"
           git add pnpm-lock.yaml
           git commit -m "chore(lockfile): refresh pnpm-lock.yaml"
-          git push
+          git push || {
+            echo "Push failed because master moved during lockfile refresh."
+            echo "A later refresh run should recompute the lockfile from the newer master state."
+            exit 1
+          }
 
       - name: Install dependencies
         run: pnpm install --frozen-lockfile