fix: add checkout and build steps to Cloudflare Pages deploy workflow

.gitea/workflows/pages-deploy.yml

@@ -9,6 +9,20 @@ jobs:
   deploy:
     runs-on: ubuntu-latest
     steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Node
+        uses: actions/setup-node@v4
+        with:
+          node-version: 20
+
+      - name: Install dependencies
+        run: cd frontend && npm ci
+
+      - name: Build
+        run: cd frontend && npm run build
+
       - name: Create deployment artifact
         run: tar -czf site.tgz -C frontend/dist .