fix: 优化 ImageMessage 的 URL 处理逻辑，简化代码并保持特殊字符转义支持

util/url.go

@@ -65,6 +65,11 @@ func normalizeURL(rawURL string) string {
 
 // DownloadFile 下载文件到指定目录，返回带有正确扩展名的完整文件路径
 func DownloadFile(url string, dirPath string) (filepath string, err error) {
+
+	url = strings.ReplaceAll(url, ",", ",")
+	url = strings.ReplaceAll(url, "[", "[")
+	url = strings.ReplaceAll(url, "]", "]")
+	url = strings.ReplaceAll(url, "&", "&")
 	// 发送 HTTP GET 请求
 	var resp *http.Response
 	var maxRetry = 100