dsh-midtalk: In-Task Interjection + Optional Barge-in + Structured Resume Card

`dsh-midtalk` is a Host-side workflow plugin for DeepSeek Harness (DSH), designed to address the operational challenges of "intervening" and "interrupting" during task execution. It implements two slash commands: `/say` for lossless intervention, inserting input at step boundaries; and `/cut` for lossy interruption, which aborts the current step and generates a structured recovery card containing the full state. Installation supports command-line or manual mounting, with no third-party dependencies. This tool helps users fine-grained control over the task workflow and is suitable for intervening at any time during long-running tasks.