dsh-payload: Inspect the actual request of every model call in DSH

The plugin `shengpj/dsh-payload` offers a "View Request JSON" entry for every assistant reply. The popup displays the `model`, call parameters, `messages`, `tools`, token breakdown, and context source distribution of the specific call that generated the reply. The interface is divided into a left step list grouped by calls and a right JSON area distinguishing request and response, supporting collapse, copy, and conversation linking. As a pure client-side Cordis bundle, the plugin reconstructs all data offline from session logs without resending requests or utilizing server-side interfaces. This article introduces the features, installation methods (GitHub commit pin, Plugin Market index, local link path), usage steps, logging and token metrics, limitations, and applicable scenarios, along with links to the community directory and repository.