dsh-todo-progress-hud: Transform the agent's todo list into a persistent progress bar above the input box

When DSH runs long tasks, the agent uses `todo_write` to maintain a list, but the list is hidden within the session panel, making the progress invisible. `dsh-todo-progress-hud` reads the session projection to transform the same list into a persistent progress bar above the input box, displaying completion percentage, current step, and the status of each item in real-time. It supports expanding/collapsing, status coloring, failure alerts, and a dark theme. It requires no tool permissions and makes no network requests, and is mounted to the `conversation.input.dock` slot. Requires DSH >= 0.2.0 and is available for Web/Desktop only. MIT license, maintained by heisedexiaoniukou-max.