dsh-query-jump: DSH WebUI Session Query Navigation

The DeepSeek Harness (DSH) plugin `dsh-query-jump` is designed specifically to help locate historical queries in ultra-long conversations. By rendering an unobtrusive track along the right edge of the chat area, it enables hover-to-expand access to a list of past queries and offers rich features such as smooth scrolling and positioning, current-position highlighting, custom prefixes, and session deletion. Beyond recording real user queries, the plugin also supports historical data synchronization and cache synchronization, delivering an efficient and smooth context-retrospective experience for agent development.