feat(deployment): add QEMU setup for cross-platform builds and improve Docker Buildx configuration

.gitea/workflows/deploy-production.yaml

@@ -16,6 +16,12 @@ jobs:
         uses: https://github.com/actions/checkout@v4
         with:
           persist-credentials: false
+      - name: Set up QEMU for cross-platform builds
+        uses: https://github.com/docker/setup-qemu-action@v3
+        with:
+          platforms: amd64,arm64
+          # Gitea does not use the GitHub Actions cache backend.
+          cache-image: false
       - name: Build and push to Gitea Packages
         shell: bash
         env:
@@ -31,14 +37,31 @@ jobs:
           : "${REGISTRY_PASSWORD:?Set REGISTRY_PASSWORD}"
           registry="${IMAGE_PREFIX%%/*}"
           auth_dir=$(mktemp -d)
-          trap 'rm -rf -- "$auth_dir"' EXIT
+          builder_name=""
+          cleanup() {
+            local rc=$?
+            if [[ -n "$builder_name" ]]; then
+              docker buildx rm "$builder_name" >/dev/null || true
+            fi
+            rm -rf -- "$auth_dir"
+            exit "$rc"
+          }
+          trap cleanup EXIT
+          trap 'exit 130' INT
+          trap 'exit 143' TERM
           export DOCKER_CONFIG="$auth_dir"
+          export BUILDX_CONFIG="$auth_dir/buildx"
           printf '%s' "$REGISTRY_PASSWORD" | docker login "$registry" --username "$REGISTRY_USERNAME" --password-stdin
           unset REGISTRY_PASSWORD
-          docker build --pull --load --platform "${BUILD_PLATFORM:-linux/amd64}" \
+          # Create after selecting the isolated config; do not change the runner's default builder.
+          builder_name=$(docker buildx create --driver docker-container)
+          docker info --format 'Build host: {{.OSType}}/{{.Architecture}}'
+          echo "Target platform: ${BUILD_PLATFORM:-linux/amd64}"
+          docker buildx inspect "$builder_name" --bootstrap
+          docker buildx build --builder "$builder_name" --pull --load --platform "${BUILD_PLATFORM:-linux/amd64}" \
             --label "org.opencontainers.image.revision=$DEPLOY_TAG" \
             -f Dockerfile.backend -t "$IMAGE_PREFIX-backend:$DEPLOY_TAG" .
-          docker build --pull --load --platform "${BUILD_PLATFORM:-linux/amd64}" \
+          docker buildx build --builder "$builder_name" --pull --load --platform "${BUILD_PLATFORM:-linux/amd64}" \
             --label "org.opencontainers.image.revision=$DEPLOY_TAG" \
             -f Dockerfile.frontend -t "$IMAGE_PREFIX-web:$DEPLOY_TAG" .
           docker push "$IMAGE_PREFIX-backend:$DEPLOY_TAG"