ci: add docker build workflow

.github/workflows/docker.yml

@@ -0,0 +1,65 @@
+name: Build and Push Docker Images
+
+on:
+  pull_request:
+    branches:
+      - main
+  release:
+    types:
+      - published
+
+env:
+  REGISTRY: ghcr.io
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+    strategy:
+      matrix:
+        include:
+          - name: backend
+            dockerfile: docker/backend.Dockerfile
+            image: ${{ github.repository_owner }}/patchmon-backend
+          - name: frontend
+            dockerfile: docker/frontend.Dockerfile
+            image: ${{ github.repository_owner }}/patchmon-frontend
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.repository_owner }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Extract metadata (tags, labels)
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ env.REGISTRY }}/${{ matrix.image }}
+          tags: |
+            type=ref,event=pr
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=semver,pattern={{major}}
+            type=raw,value=latest,enable={{is_default_branch}}
+
+      - name: Build and push ${{ matrix.name }} image
+        uses: docker/build-push-action@v5
+        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.name }}
+          cache-to: type=gha,mode=max,scope=${{ matrix.name }}