edit-chat-dsh: Editing DeepSeek Harness Chat Prompts via Branching and Resending

The `edit-chat-dsh` plugin provides branching and resubmission functionality for prompt editing in the DeepSeek Harness (DSH) client. Since DSH's native editing workflow lacks state management, the plugin introduces a branching mechanism to resolve state-control issues caused by frequent prompt modifications. Users should refer to the source code for installation instructions and verify security before use. This plugin is suitable for users who need versioned prompt management in DSH.