ci: gate publish on format:check

Prevent the 1.1.8-class drift where format-check CI failed but publish shipped anyway (caught by supply-chain witness audit of the barn/wheat rapid-release burst).

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

Author: aid-ninja

.github/workflows/publish.yml

@@ -37,6 +37,9 @@ jobs:
       - name: Install
         run: npm ci
 
+      - name: Format check
+        run: npm run format:check
+
       - name: Test
         run: npm test