ci: build and push docker image on each commit

.github/workflows/docker-image.yml

@@ -0,0 +1,25 @@
+name: Docker Image CI
+
+on:
+  push:
+    branches:
+      - "master"
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Login to Docker Hub
+        uses: docker/login-action@v3
+        with:
+          username: ${{ vars.DOCKER_HUB_USERNAME }}
+          password: ${{ secrets.DOCKER_HUB_TOKEN }}
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Build and push
+        uses: docker/build-push-action@v6
+        with:
+          push: true
+          tags: ${{ vars.DOCKERHUB_USERNAME }}/standalone-nuvotifier:latest