feat(ci): add staging deployment workflow

.github/workflows/staging.yml

@@ -0,0 +1,73 @@
+name: Staging Deploy
+
+on:
+  push:
+    branches: [staging]
+  workflow_dispatch:
+
+permissions:
+  contents: read
+  packages: write
+
+jobs:
+  build-and-deploy:
+    name: Build & Deploy to Staging
+    runs-on: ubuntu-latest
+    environment: staging
+    
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+          cache: 'npm'
+          
+      - name: Install dependencies
+        run: npm ci
+        
+      - name: Install backend dependencies
+        working-directory: ./backend
+        run: npm ci
+        
+      - name: Lint
+        run: npm run lint
+        
+      - name: Run tests
+        run: npm run test:run
+        
+      - name: Build
+        run: npm run build
+        
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+        
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+        
+      - name: Login to Docker Hub
+        uses: docker/login-action@v3
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+          
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+          
+      - name: Build and push
+        uses: docker/build-push-action@v5
+        with:
+          context: .
+          platforms: linux/amd64,linux/arm64
+          push: true
+          tags: |
+            ${{ secrets.DOCKERHUB_USERNAME }}/cv-app:staging
+            ghcr.io/${{ github.repository_owner }}/cv-app:staging
+          cache-from: type=gha
+          cache-to: type=gha,mode=max