Enable openssl-legacy-provider for webpack 4 build on Node 20

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: lmcmz

.github/workflows/firebase-hosting-merge.yml

@@ -28,6 +28,7 @@ jobs:
         run: npm run build
         env:
          CI: false
+         NODE_OPTIONS: --openssl-legacy-provider
       - uses: FirebaseExtended/action-hosting-deploy@v0
         with:
           repoToken: '${{ secrets.GITHUB_TOKEN }}'