build(Dockerfile): 优化Go依赖下载并设置代理环境变量

添加Go环境变量配置和代理设置，并实现依赖下载的重试机制以提高构建可靠性

Dockerfile

@@ -10,8 +10,22 @@ RUN apk add --no-cache git ca-certificates tzdata
 # Copy go mod files
 COPY go.mod go.sum ./
 
-# Download dependencies
+# Set Go environment variables and proxy
-RUN go mod download
+ENV GO111MODULE=on \
+    CGO_ENABLED=0 \
+    GOOS=linux \
+    GOARCH=amd64 \
+    GOPROXY=https://goproxy.cn,https://goproxy.io,direct \
+    GOSUMDB=sum.golang.google.cn
+
+# Download dependencies with retry mechanism
+RUN go mod download || \
+    (echo "Retrying with different proxy..." && \
+     go env -w GOPROXY=https://goproxy.io,https://mirrors.aliyun.com/goproxy/,direct && \
+     go mod download) || \
+    (echo "Final retry with direct mode..." && \
+     go env -w GOPROXY=direct && \
+     go mod download)
 
 # Copy source code
 COPY . .