add build workflow for backend application and Docker image

.gitea/workflows/build.yml

@@ -0,0 +1,35 @@
+name: Build Backend Application and Docker Image
+
+on:
+  push:
+    branches:
+      - main
+  workflow_dispatch:
+
+jobs:   
+  build-docker:
+    needs: build-backend
+    runs-on: ubuntu-latest
+    permissions:
+      packages: write
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v3
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: git.siwatsystem.com
+          username: ${{ github.actor }}
+          password: ${{ secrets.RUNNER_TOKEN }}
+        
+      - name: Build and push Docker image
+        uses: docker/build-push-action@v4
+        with:
+          context: .
+          file: ./Dockerfile
+          push: true
+          tags: git.siwatsystem.com/adsist-cms/worker:latest