feat: add CI workflow for building and deploying demo to ghpages

Author: mnixry

.github/workflows/ci.yml

@@ -0,0 +1,45 @@
+name: CI
+
+on:
+  push:
+  pull_request:
+  workflow_dispatch:
+
+permissions:
+  contents: read
+  pages: write
+  id-token: write
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: false
+
+jobs:
+  build:
+    name: Build
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@main
+      - uses: DeterminateSystems/determinate-nix-action@main
+      - uses: DeterminateSystems/magic-nix-cache-action@main
+      - name: Run Nix Build
+        run: |
+          nix build .#demo --print-build-logs
+      - uses: actions/upload-pages-artifact@main
+        if: github.ref == 'refs/heads/main'
+        with:
+          path: result
+
+  deploy:
+    name: Deploy
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    needs: build
+    runs-on: ubuntu-latest
+    if: github.ref == 'refs/heads/main'
+    steps:
+      - name: Deploy to GitHub Pages
+        id: deployment
+        uses: actions/deploy-pages@main