chore: add GitHub Actions workflow for Docker build and publish

Author: nickytonline

.github/workflows/docker.yml

@@ -0,0 +1,61 @@
+name: docker
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+
+env:
+  REGISTRY: docker.io
+  IMAGE_NAME: dev-to-mcp
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Build image for validation
+        uses: docker/build-push-action@v5
+        with:
+          context: .
+          file: Dockerfile
+          push: false
+          tags: ${{ env.IMAGE_NAME }}:ci-${{ github.sha }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
+
+  publish:
+    if: github.event_name == 'push' && github.ref == 'refs/heads/main'
+    needs: build
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to Docker Hub
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - name: Build and push image
+        uses: docker/build-push-action@v5
+        with:
+          context: .
+          file: Dockerfile
+          push: true
+          tags: |
+            ${{ env.REGISTRY }}/${{ secrets.DOCKERHUB_USERNAME }}/${{ env.IMAGE_NAME }}:latest
+            ${{ env.REGISTRY }}/${{ secrets.DOCKERHUB_USERNAME }}/${{ env.IMAGE_NAME }}:${{ github.sha }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max