复制模式添加秒传/相同文件跳过复制，多选文件时显示选中文件数量

### Please make sure of the following things

- [x] I have read the [documentation](https://alist.nn.ci).
- [x] I'm sure there are no duplicate issues or discussions.
- [x] I'm sure this feature is not implemented.
- [x] I'm sure it's a reasonable and popular requirement.

### Description of the feature / 需求描述

复制模式添加秒传/相同文件跳过复制
多选文件时显示选中文件数量

### Suggested solution / 实现思路

_No response_

### Additional context / 附件

_No response_