Add staging deployment workflow

.forgejo/workflows/staging.yml

@@ -0,0 +1,35 @@
+name: Deploy to Staging
+
+on:
+  push:
+    branches:
+      - staging
+  workflow_dispatch:
+
+jobs:
+  deploy:
+    runs-on: linux-amd64
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '22'
+
+      - name: Install pnpm
+        uses: pnpm/action-setup@v4
+        with:
+          version: 10.11.0
+
+      - name: Install dependencies
+        run: pnpm install
+
+      - name: Build
+        run: pnpm build:vdn-static
+
+      - name: Deploy to staging
+        run: |
+          rm -rf /var/www/staging.viossa.net/*
+          cp -r apps/vdn-static/dist/* /var/www/staging.viossa.net/