图片上传

大佬好，目前工具已支持打开本地文件夹内的 .md文件，想新增批量上传功能：可批量读取当前 Markdown 文件内容并将其中图片批量上传至图床，方便处理已完成的文档，无需每次从零新建编写。

Start by tracing the existing local-folder Markdown opening flow and the current image-upload or image-hosting flow. Add batch handling for images referenced by the opened Markdown document, then verify that completed documents upload their images without requiring a new document and that the resulting content remains usable.

Written by the indexing model from the issue text.