Ls Tool lack detail infomations of return entries

如图，模型使用 **ls** 工具无法区分是文件还是目录，会错误的将文件当做目录进一步探索导致报错

且建议加上文件的详细信息，比如内存大小，否则如果文件是二进制可执行文件，就会导致工具返回结果过大，污染上下文

Start by locating the Go implementation and output formatting for the ls tool, then reproduce the reported case from the screenshots where files are mistaken for directories. Done means returned entries distinguish files from directories and provide useful file-size information without producing excessively large results.

Written by the indexing model from the issue text.