dsh-file-picker: Native Windows File Picker Plugin

This plugin is maintained by JackeyWilder and is designed to address the need for DeepSeek Harness (DSH) agents to directly access the local file system. It provides a native Windows file picker, allowing users to select a file and inject its path into a draft in the format `@path:`. Since no official installation command is available, users need to obtain the source code from the GitHub repository. Given that the plugin relies on local system interactions and has an unclear origin, users are advised to inspect the source code themselves to confirm its security and licensing terms.