vlln/dsh-task-status: Display Background Task Status on DSH Chat Page

`vlln/dsh-task-status` is an example plugin in the DSH ecosystem, designed to address the lack of background task status entry points on the Web-side Chat page. The plugin displays the number of running background tasks above the conversation input box, allowing users to click on a task row to expand and view its status, duration, and the latest output tail (limited to 10 lines/160px, with scrolling support). It only takes effect on the Chat page, and the status bar automatically disappears once the task is completed. Core functionalities include providing read-only `/tasks` list and `/output` tail routes, and applying a mirror patch to `ctx.tasks.read` to synchronize incremental output reading semantics. Installation requires a specific git source command, and it demands Node.js >=22.19.0 and dsh >2.0.0.