dsh-plugin-md-outline: DSH Markdown Outline and Structure Check Plugin

dsh-plugin-md-outline is a DeepSeek Harness (DSH) plugin maintained by d-ouyang. Written in pure ESM JavaScript and released under the MIT license, it requires no build steps. It aims to automate the resolution of structural issues in long Markdown documents by adding the `md_outline` tool, enabling the automatic output of the document title tree and structural checks. Core features include outputting an H1-H6 nested title tree with line numbers, as well as detecting heading level jumps, duplicate headings, H1 uniqueness issues, and unclosed code fences. The plugin supports three modes: `outline`, `lint`, and `both`. It allows limiting the outline depth via `maxDepth` and supports recursive scanning of directories.