Add GitHub Actions workflow for Pages deployment

- Uses reusable workflow from toolkit repository
- Automatically deploys on push to main branch
- Updates toolkit submodule reference

Author: seghcder

.github/workflows/deploy.yml

@@ -0,0 +1,34 @@
+# Deploy Singapore RBO Website to GitHub Pages
+# Uses reusable workflow from the toolkit repository
+
+name: Deploy to GitHub Pages
+
+on:
+  push:
+    branches: [main]
+  workflow_dispatch:
+
+permissions:
+  contents: read
+  pages: write
+  id-token: write
+
+concurrency:
+  group: "pages"
+  cancel-in-progress: false
+
+jobs:
+  build:
+    uses: digitaltwinconsortium/rbo_website_toolkit/.github/workflows/build-site.yml@main
+
+  deploy:
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    runs-on: ubuntu-latest
+    needs: build
+    steps:
+      - name: Deploy to GitHub Pages
+        id: deployment
+        uses: actions/deploy-pages@v4
+