dsh-ui-state: DeepSeek Harness UI State Persistence Plugin

The Web GUI of DeepSeek Harness loses its state after a restart. This plugin is designed to persist the interface state. It supports restoring the sidebar's expanded or collapsed state and width, recording the details panel's on/off state, and saving the conversation scroll position. The plugin adopts event-driven and batch-write mechanisms to optimize performance, and can be installed via CLI without configuration. It is compatible with DSH 0.1.x versions and provides robust fault tolerance and mobile responsiveness.