add CI workflow

.github/workflows/ci.yml

@@ -0,0 +1,51 @@
+name: Build and publish Docker image
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    branches:
+      - master
+  workflow_dispatch:
+
+permissions:
+  contents: read
+  packages: write
+
+jobs:
+  ci:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v2
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+
+      - name: Login to GitHub Container Registry
+        if: github.event_name == 'push'
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Derive lowercase image metadata
+        run: |
+          REPO_URI_LOWERCASE=$(echo '${{ github.repository }}' | tr '[:upper:]' '[:lower:]')
+          echo "IMAGE_PREFIX_LOWERCASE=ghcr.io/$REPO_URI_LOWERCASE" >> $GITHUB_ENV
+
+      - name: Build and push
+        uses: docker/build-push-action@v4
+        with:
+          platforms: linux/amd64,linux/arm64
+          push: ${{ github.event_name == 'push' }}
+          tags: |
+            ${{ env.IMAGE_PREFIX_LOWERCASE }}:latest
+            ${{ env.IMAGE_PREFIX_LOWERCASE }}:${{ github.sha }}
+          labels: |
+            org.opencontainers.image.source=${{ github.server_url }}/${{ github.repository }}