dsh-conversation-outline: Add a right-side navigation bar for long DSH Web conversations

`dsh-conversation-outline` is a MIT-licensed client-side plugin for the DeepSeek Harness (DSH) web interface, designed to solve the problem of quickly locating historical issues in long conversations. It provides a navigation bar on the right edge, displaying all questions in chronological order as vertical bars. Core features include: hover previews showing the beginning words, turn badges, and timestamps of questions; clicking a vertical bar switches to the Chat view and scrolls to the corresponding message, accompanied by a flashing prompt for easy identification; case-insensitive question search and paginated loading of historical conversations; and real-time tracking, where new questions appear instantly. The plugin supports bilingual Chinese and English, runs with zero dependencies, requires no additional network calls or telemetry, and can be installed via GitHub, npm (if published), or local source code, with Node.js as a requirement.