add GitHub Actions DApp deployment workflow

.github/workflows/deploy-dapp.yml

@@ -0,0 +1,53 @@
+name: Deploy Dapp
+
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  build:
+    name: Build
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+
+      - name: Set up Node.js
+        uses: actions/setup-node@v2
+        with:
+          node-version: '14'
+
+      - name: Install dependencies
+        run: npm install
+        working-directory: ./dapp
+
+      - name: Build project
+        run: npm run build
+        working-directory: ./dapp
+
+      - name: Upload production-ready build files
+        uses: actions/upload-artifact@v2
+        with:
+          name: production-files
+          path: ./dapp/dist
+
+  deploy:
+    name: Deploy
+    needs: build
+    runs-on: ubuntu-latest
+    if: github.ref == 'refs/heads/main'
+
+    steps:
+      - name: Download artifact
+        uses: actions/download-artifact@v2
+        with:
+          name: production-files
+          path: ./dapp/dist
+
+      - name: Deploy to GitHub Pages
+        uses: peaceiris/actions-gh-pages@v3
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          publish_dir: ./dapp/dist