qp-exa-dynamic: Exa Dynamic Highlighting Support and Web Search Runtime Configuration

`qp-exa-dynamic` is a plugin developed for DeepSeek Harness (DSH) that enables web search via the Exa backend and resolves the inability of the native Exa provider to use dynamic highlights. It enables Exa Dynamic Highlights by default and supports multiple retrieval types, including keyword and neural. Users can use the `/exa` command to adjust highlights, retrieval type, and result count in real time. The `exa_search` tool registered by the plugin is not subject to the default limit, allowing up to 50 results. During installation, you need to override the `web` provider in the configuration and set the API Key.