ci: build previws for the website on doc changes

.github/workflows/docs-preview.yml

@@ -0,0 +1,78 @@
+name: Build and Preview Manual
+
+on:
+  workflow_dispatch:
+  pull_request:
+    types: [opened, synchronize, reopened]
+    paths:
+      - ".github/workflows/docs-preview.yml"
+      - "modules/**"
+      - "docs/**"
+
+jobs:
+  build-preview:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+      pull-requests: write
+
+    steps:
+      - name: Install Nix
+        uses: DeterminateSystems/nix-installer-action@main
+      - uses: DeterminateSystems/magic-nix-cache-action@main
+
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set default git branch (to reduce log spam)
+        run: git config --global init.defaultBranch main
+
+      - name: Build documentation packages
+        run: nix build .#docs-html --print-build-logs
+
+      - name: Deploy to GitHub Pages preview
+        run: |
+          PR_NUMBER=${{ github.event.pull_request.number }}
+          BRANCH_NAME="gh-pages"
+          PREVIEW_DIR="docs-preview-${PR_NUMBER}"
+
+          # Clone the gh-pages branch and move to the preview subdirectory
+          git clone --single-branch --branch $BRANCH_NAME https://github.com/${{ github.repository }} gh-pages
+          cd gh-pages
+
+          mkdir -p $PREVIEW_DIR
+
+          # Copy the build files to the preview subdirectory
+          cp -rvf ../result/share/doc/nvf/* ./$PREVIEW_DIR
+
+          # Configure git to use the GitHub Actions token for authentication
+          git config --global user.name "GitHub Actions"
+          git config --global user.email "[email protected]"
+
+          # Set the GitHub token for authentication
+          git remote set-url origin https://x-access-token:${{ secrets.GITHUB_TOKEN }}@github.com/${{ github.repository }}
+
+          # Add and commit the changes
+          git add .
+          git commit -m "Deploy PR #${PR_NUMBER} preview"
+          git push origin $BRANCH_NAME
+
+      - name: Set preview URL
+        id: set-url
+        run: |
+          PR_NUMBER=${{ github.event.pull_request.number }}
+          URL="https://<username>.github.io/<repo-name>/pr-preview-${PR_NUMBER}/"
+          echo "Live Preview URL: $URL"
+          echo "::set-output name=url::$URL"
+
+  comment-url:
+    needs: build-preview
+    runs-on: ubuntu-latest
+    steps:
+      - name: Post live preview comment
+        uses: peter-evans/create-or-update-comment@v4
+        with:
+          issue-number: ${{ github.event.pull_request.number }}
+          body: |
+            🚀 Live preview is ready!
+            You can view it here: ${{ needs.build.outputs.url }}