dsh-tool-ast-grep: AST-based Structural Code Search and Outline Tool

`dsh-tool-ast-grep` is a core plugin in the DeepSeek Harness (DSH) ecosystem, designed to address the high token consumption and low semantic accuracy of traditional regular expression searching. Based on the `ast-grep` engine, it provides AST-level structured code search and syntax outline extraction capabilities. Its core features include: `ast_search` with metavariable support, `ast_outline` structural extraction that saves 80%–95% of tokens, and subprocess-safe calls that are immune to shell escaping issues. It supports multiple languages, including TypeScript, Python, Rust, and Go. To install the plugin, install the `ast-grep` CLI first and enable it via the `dsh plugin` command, which can