feat: add production container publishing

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

.github/workflows/publish-image.yml

@@ -0,0 +1,59 @@
+name: Publish Docker image
+
+on:
+  push:
+    branches:
+      - master
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+env:
+  IMAGE_NAME: batty1039.startdedicated.net:5000/go-guess
+  FORCE_JAVASCRIPT_ACTIONS_TO_NODE24: true
+
+jobs:
+  publish-image:
+    name: Build and push Docker image
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Check out source
+        uses: actions/checkout@v5
+
+      - name: Configure HTTP registry
+        run: |
+          sudo mkdir -p /etc/docker
+          echo '{"insecure-registries":["batty1039.startdedicated.net:5000"]}' | \
+            sudo tee /etc/docker/daemon.json >/dev/null
+          sudo systemctl restart docker
+          cat > /tmp/buildkitd.toml <<'EOF'
+          [registry."batty1039.startdedicated.net:5000"]
+            http = true
+            insecure = true
+          EOF
+
+      - name: Log in to private registry
+        uses: docker/login-action@v4
+        with:
+          registry: batty1039.startdedicated.net:5000
+          username: ${{ secrets.REGISTRY_USERNAME }}
+          password: ${{ secrets.REGISTRY_PASSWORD }}
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v4
+        with:
+          buildkitd-config: /tmp/buildkitd.toml
+
+      - name: Build and push image
+        uses: docker/build-push-action@v7
+        with:
+          context: .
+          file: ./Dockerfile
+          push: true
+          tags: |
+            ${{ env.IMAGE_NAME }}:latest
+            ${{ env.IMAGE_NAME }}:${{ github.sha }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max