add docker build action

Signed-off-by: Sid Sun <sid@sidsun.com>

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

@@ -0,0 +1,28 @@
+name: Docker Image Build and Push CI
+
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  build-and-push:
+    runs-on: ubuntu-latest
+    environment: prod
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to DockerHub
+        uses: docker/#-action@v3
+        with:
+          username: ${{ secrets.DOCKER_USERNAME }}
+          password: ${{ secrets.DOCKER_PASSWORD }}
+
+      - name: Build and push Docker image
+        run: |
+          docker buildx build --platform linux/amd64,linux/arm64,linux/arm/v7 -t realsidsun/ntfy.tg:latest --push .