ci(docker): 更新 Docker镜像构建和推送流程

- 添加 Docker Hub 登录步骤
- 更新镜像标签为 latest
- 增加镜像推送步骤

.github/workflows/docker-image.yml

@@ -7,12 +7,17 @@ on:
     branches: [ "main" ]
 
 jobs:
-
   build:
-
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v4
-    - name: Build the Docker image
-      run: docker build . --file Dockerfile --tag kpxyyyy/dnsmgr:$(date +%s)
+      - uses: actions/checkout@v4
+
+      - name: Log in to Docker Hub
+        run: echo "${{ secrets.DOCKER_PASSWORD }}" | docker login -u "${{ secrets.DOCKER_USERNAME }}" --password-stdin
+
+      - name: Build the Docker image
+        run: docker build . --file Dockerfile --tag kpxyyyy/dnsmgr:latest
+
+      - name: Push the Docker image
+        run: docker push kpxyyyy/dnsmgr:latest