ci: add GitHub Actions workflow to publish Docker images to GHCR

.github/workflows/docker-publish.yml

@@ -0,0 +1,75 @@
+name: Build and Publish Docker Images to GHCR
+
+on:
+  release:
+    types: [published]
+  workflow_dispatch:
+    inputs:
+      tag:
+        description: "Docker image tag"
+        required: true
+        default: "latest"
+
+env:
+  REGISTRY: ghcr.io
+
+jobs:
+  build-and-push:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+
+    strategy:
+      matrix:
+        include:
+          - image: backend
+            dockerfile: docker/dockerfiles/backend.Dockerfile
+          - image: frontend
+            dockerfile: docker/dockerfiles/frontend.Dockerfile
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          ref: ${{ github.event.release.tag_name || github.event.inputs.tag }}
+
+      - name: Set up QEMU (for multi-platform builds)
+        uses: docker/setup-qemu-action@v3
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to GHCR
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Set image prefix
+        id: repo
+        run: echo "image_prefix=${{ env.REGISTRY }}/${GITHUB_REPOSITORY,,}" >> $GITHUB_OUTPUT
+
+      - name: Extract metadata
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ steps.repo.outputs.image_prefix }}/${{ matrix.image }}
+          tags: |
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=raw,value=latest,enable=${{ github.event_name == 'release' }}
+            type=raw,value=${{ github.event.inputs.tag }},enable=${{ github.event_name == 'workflow_dispatch' }}
+
+      - name: Build and push ${{ matrix.image }}
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          file: ${{ matrix.dockerfile }}
+          platforms: linux/amd64,linux/arm64
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          cache-from: type=gha,scope=${{ matrix.image }}
+          cache-to: type=gha,mode=max,scope=${{ matrix.image }}