Fix PR preview by passing github-token to download-artifact

download-artifact silently ignores run-id unless github-token is also
provided, so the action was searching the current (preview) run instead
of the triggering Build run. Broken since the switch from
dawidd6/action-download-artifact in 35f8690.

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

Author: holly-cummins

.github/workflows/preview.yml

@@ -20,6 +20,7 @@ jobs:
       - name: Download PR Artifact
         uses: actions/download-artifact@v8
         with:
+          github-token: ${{ github.token }}
           run-id: ${{ github.event.workflow_run.id }}
           name: site
       - name: Store PR id as variable