dsh-context-tree: Reusable Trajectory Tree Context for DeepSeek Harness

`dsh-context-tree` is a DeepSeek Harness plugin maintained by wr-web, designed to address the lack of intuitive management when reusing context across sessions. It converts completed turns into visualized, branchable checkpoints, enables resumption from any precise point, and controls the recall scope to reduce redundant exploration. Through a bounded recall mechanism (limiting node lifetime and size) and token accounting, the plugin makes context reuse measurable and is suited for development scenarios that require long-term maintenance of agent sessions.