Add Docker workflow for backend image build

.github/workflows/docker-build-and-push-backend.yml

@@ -0,0 +1,73 @@
+name: Build and Push Docker Image of Backend
+
+on:
+  push:
+    branches: [ main, development ]
+    paths:
+      - '.github/workflows/docker-build-and-push-backend.yml'
+      - 'backend/**'
+      - '!backend/README.md'
+
+  workflow_dispatch: # Allow manual trigger
+
+
+env:
+  REGISTRY: ghcr.io
+  NAMESPACE: ${{ github.repository_owner }}
+  IMAGE_NAME: committee-clash-backend
+  IMAGE_TAG: "latest${{ github.ref == 'refs/heads/main' && '' || '-dev' }}" # TODO does not support versioning as of yet
+
+
+concurrency:
+  group: "docker-backend"
+  cancel-in-progress: false
+
+
+jobs:
+  build-and-push:
+    name: Build and Push Docker Image
+    runs-on: ubuntu-latest
+    environment: ${{ github.ref == 'refs/heads/main' && 'production' || 'development' }}
+    permissions:
+      contents: read
+      packages: write
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v5
+
+    - name: Downcase NAMESPACE
+      run: |
+        echo "NAMESPACE=${NAMESPACE,,}" >>${GITHUB_ENV}
+
+    - name: Set up Docker Buildx
+      uses: docker/setup-buildx-action@v3
+
+    - name: Log in to Container Registry
+      uses: docker/login-action@v3
+      with:
+        registry: ${{ env.REGISTRY }}
+        username: ${{ github.actor }}
+        password: ${{ secrets.GITHUB_TOKEN }}
+
+    - name: Build and push Docker image
+      uses: docker/build-push-action@v6
+      with:
+        context: ./backend/
+        file: ./backend/Dockerfile
+        push: true
+        tags: ${{ env.REGISTRY}}/${{ env.NAMESPACE }}/${{ env.IMAGE_NAME }}:${{ env.IMAGE_TAG }}
+        cache-from: type=gha
+        cache-to: type=gha,mode=max
+
+    - name: Generate deployment info
+      run: |
+        echo "## Deployment Information" >> $GITHUB_STEP_SUMMARY
+        echo "**Image**: \`${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:latest\`" >> $GITHUB_STEP_SUMMARY
+        echo "**Registry**: GitHub Container Registry" >> $GITHUB_STEP_SUMMARY
+        echo "**Branch**: ${{ github.ref_name }}" >> $GITHUB_STEP_SUMMARY
+        echo "**Commit**: ${{ github.sha }}" >> $GITHUB_STEP_SUMMARY
+
+#    - name: Trigger watchtower
+#      run: |
+#        curl -fH "Authorization: Bearer ${{ secrets.WATCHTOWER_TOKEN }}" ${{ secrets.API_URL }}:8080/v1/update