Add Docker support with CI/CD workflow and usage instructions

- Added `.github/workflows/docker-image.yml` for automated Docker image build and push on version tags.
- Created `Dockerfile` to containerize the application.
- Updated README with instructions for running the application using Docker.

.github/workflows/docker-image.yml

@@ -0,0 +1,42 @@
+name: docker-image
+
+on:
+  push:
+    tags:
+      - v*
+
+env:
+  APP_NAME: CLIProxyAPI
+  DOCKERHUB_REPO: eceasy/cli-proxy-api
+
+jobs:
+  docker:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+      - name: Login to DockerHub
+        uses: docker/login-action@v3
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+      - name: Generate App Version
+        run: echo APP_VERSION=`git describe --tags --always` >> $GITHUB_ENV
+      - name: Build and push
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          platforms: |
+            linux/amd64
+            linux/arm64
+          push: true
+          build-args: |
+            APP_NAME=${{ env.APP_NAME }}
+            APP_VERSION=${{ env.APP_VERSION }}
+          tags: |
+            ${{ env.DOCKERHUB_REPO }}:latest
+            ${{ env.DOCKERHUB_REPO }}:${{ env.APP_VERSION }}