[CI] create a deployment preview for changes to the shape builder site

.github/workflows/build-and-preview-site.yml

@@ -1,32 +1,78 @@
 name: Build and Preview Site
+
 on:
-  pull_request:
+  pull_request_target:
     branches: [master]
-    types: [opened, synchronize, reopened]
+    types: [opened, synchronize, reopened, closed]
+
+permissions:
+  contents: write
+  pull-requests: write
+
+concurrency:
+  group: "preview-${{ github.event.pull_request.number || github.run_id }}"
+  cancel-in-progress: true
 
 jobs:
-  site-preview:
-    runs-on: ubuntu-latest
+  build-and-deploy-preview:
+    runs-on: ubuntu-24.04
     steps:
-      - name: Checkout 🛎️
-        uses: actions/checkout@master
+      - name: Checkout PR
+        if: github.event.action != 'closed'
+        uses: actions/checkout@v6
         with:
+          repository: ${{ github.event.pull_request.head.repo.full_name }}
+          ref: ${{ github.event.pull_request.head.sha }}
           persist-credentials: false
-          fetch-depth: 1
+          fetch-depth: 0
 
-      - name: Install and Build 🔧
+      - name: Checkout for cleanup
+        if: github.event.action == 'closed'
+        uses: actions/checkout@v6
+        with:
+          ref: gh-pages
+          fetch-depth: 0
+
+      - name: Install and Build
+        if: github.event.action != 'closed'
         run: |
           make setup
           make build
 
-      - name: Zip Site
-        run: bash ./script.sh
+      - name: Add robots.txt for previews
+        if: github.event.action != 'closed'
+        run: |
+          cat > site/public/robots.txt <<'EOF'
+          User-agent: *
+          Disallow: /
+          EOF
+
+      - name: Deploy PR preview
+        if: github.event.action != 'closed'
+        uses: rossjrw/pr-preview-action@v1.6.3
+        with:
+          source-dir: ./site/public
+          preview-branch: gh-pages
+          umbrella-dir: pr-preview
+          action: auto
+          comment: false
+
+      - name: Comment PR with Preview URL
+        if: github.event.action != 'closed'
+        uses: marocchino/sticky-pull-request-comment@v2
+        with:
+          header: pr-preview
+          message: |
+            🚀 **Preview deployment for PR #${{ github.event.pull_request.number }}**
+
+            🌐 **Preview URL**: https://${{ github.repository_owner }}.github.io/${{ github.event.repository.name }}/pr-preview/pr-${{ github.event.pull_request.number }}/
+
+            _This preview is updated automatically when commits are pushed to this PR._
 
-      - name: Upload files
-        uses: actions/upload-artifact@v4
+      - name: Cleanup PR preview on close
+        if: github.event.action == 'closed'
+        uses: rossjrw/pr-preview-action@v1.6.3
         with:
-          name: public-dir
-          path: public-dir.zip
-          retention-days: 1
-      - name: Trigger Inner workflow
-        run: echo "triggering inner workflow"
+          preview-branch: gh-pages
+          umbrella-dir: pr-preview
+          action: remove