Add checkout step to publish-to-pages job

The gh CLI needs to be run in a git repository to download release
assets. Add checkout step before downloading release assets.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

.github/workflows/publish-pages.yml

@@ -45,6 +45,9 @@ jobs:
       url: ${{ steps.deployment.outputs.page_url }}
 
     steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
       - name: Download web build artifact
         uses: actions/download-artifact@v4
         with: