feat: 完成网关服务代码实现，支持 WebSocket 长连接与健康检查

backend/gateway/Dockerfile

@@ -0,0 +1,19 @@
+FROM golang:1.26.1-alpine3.23 AS builder
+
+WORKDIR /app
+
+COPY go.mod ./
+COPY main.go ./
+
+RUN go mod download
+RUN go build -o gateway main.go
+
+FROM alpine:latest
+
+WORKDIR /app
+
+COPY --from=builder /app/gateway .
+
+EXPOSE 8080
+
+CMD ["./gateway"]