ci: add staging deploy workflow via SSH

Deploys to sv-frontend on push to develop.
Uses port-forwarding through UDM Pro SE (37.24.237.181:2204).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.github/workflows/deploy-staging.yml

@@ -0,0 +1,40 @@
+name: Deploy to Staging
+
+on:
+  push:
+    branches: [develop]
+  workflow_dispatch:
+
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+    if: github.event_name == 'workflow_dispatch' || github.ref == 'refs/heads/develop'
+    steps:
+      - name: Deploy via SSH
+        uses: appleboy/ssh-action@v1
+        with:
+          host: ${{ secrets.SSH_HOST }}
+          port: ${{ secrets.SSH_PORT }}
+          username: ${{ secrets.SSH_USER }}
+          key: ${{ secrets.SSH_PRIVATE_KEY }}
+          script_stop: true
+          script: |
+            REPO="${{ github.event.repository.name }}"
+            DIR="$HOME/${REPO}"
+            
+            echo "=== Deploying ${REPO} to staging ==="
+            cd "${DIR}" || { echo "Directory ${DIR} not found"; exit 1; }
+            
+            echo "--- Git pull ---"
+            git pull origin develop
+            
+            echo "--- Install dependencies ---"
+            pnpm install --frozen-lockfile
+            
+            echo "--- Build ---"
+            pnpm build
+            
+            echo "--- Restart PM2 (if running) ---"
+            pm2 describe "${REPO}" > /dev/null 2>&1 && pm2 restart "${REPO}" || echo "No PM2 process for ${REPO}"
+            
+            echo "=== Deploy complete ==="