chore: update demo workflow

.github/workflows/demo.yml

@@ -14,16 +14,23 @@ jobs:
       - name: Checkout repo
         uses: actions/checkout@v4
 
+      - name: Install pnpm
+        uses: pnpm/action-setup@v4
+        with:
+          version: 9
+          run_install: false
+
       - name: Setup Node
         uses: actions/setup-node@v4
         with:
           node-version: 20.12.2
+          cache: 'pnpm'
 
       - name: Install dependencies
-        uses: bahmutov/npm-install@v1
+        run: pnpm install
 
       - name: Build project
-        run: npm run build
+        run: pnpm build:demo
 
       - name: Upload production-ready build files
         uses: actions/upload-artifact@v4.4.3