dsh-wsl-search: Sandboxed Search Tool for WSL

`dsh-wsl-search` is a security plugin for DeepSeek Harness WSL environments. It uses a sandbox mechanism to wrap ripgrep, fd, and ast-grep, restricting searches to the `$HOME` and `~/.dsh` directories. The plugin supports content search, filename lookup, and code-structure pattern matching, with the search scope expandable by configuring the `allowRoots` field. Installation requires Node.js >= 18 and the WSL environment dependencies. This tool provides a secure and controllable solution for file analysis in WSL.