dsh-web-search-button: DeepSeek Harness Direct Web Search Plugin

`dsh-web-search-button` is a web search plugin for DeepSeek Harness, designed to address high latency, hallucinations, and excessive token consumption caused by agents relying on LLM-based search. The plugin exposes search services directly in the chat bar and can be triggered via a button or a slash command, enabling ultra-fast search with zero LLM overhead. It supports automatic lifecycle management, dark/light mode adaptation, and injects search results in Markdown format. Installation requires cloning the code, creating a directory link, and declaring the dependency in the configuration file, after which the plugin is ready to use upon restart.