DSH Question Navigator: User Question Navigation Plugin in Long Sessions

`Cocowwy/dsh-plugin-question-navigator` is a long-session question navigation plugin designed for the DeepSeek Harness (DSH) Web client. It aims to address the pain points of quickly locating user historical questions and reviewing context in long conversations without requiring modifications to the DSH source code. Integrated via the `shell.overlay` slot, this plugin supports displaying controls alongside DSH's native "Back to bottom" button. It enables one-click navigation to the most recent user message and allows sequential traversal of earlier questions, supporting both rendered and paginated history messages. The plugin adapts to light/dark/custom themes, displaying text or icons depending on the device type (desktop or mobile), and switches between Chinese and English interfaces according to the browser language. It requires DSH Web 0.1.0-rc.6 or later.