Add action to build and deploy

.github/workflows/deploy-ghpages.yml

@@ -0,0 +1,22 @@
+on:
+  pull_request:
+  push:
+    branches: [main]
+
+jobs:
+  build_and_deploy:
+    name: Build and Deploy
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: DeterminateSystems/nix-installer-action@main
+
+      - name: Build
+        run: nix build .#blog
+
+      - name: Deploy
+        uses: peaceiris/actions-gh-pages@v3
+        with:
+            github_token: ${{ secrets.GITHUB_TOKEN }}
+            publish_dir: ./result