dsh-pomodoro: Adding a Pomodoro Timer to DSH Web

`dsh-pomodoro` is an MIT-licensed plugin designed specifically for the DeepSeek Harness (DSH) web interface, aimed at integrating a focus timer into the working environment. The plugin provides a sidebar entry and a draggable overlay, supporting customizable focus and break durations, phase controls (start, pause, reset, skip), a circular progress display, and in-app reminders with optional system notifications. It features a Mini compact mode, state persistence (automatic timer restoration after restart), bilingual language switching between Chinese and English, and adapts to DSH light/dark themes and accessibility preferences. Installation requires DSH `>=0.1.0-rc.7`, Node.js `^22.19.0` or `>=24.0.0`, and running under the `web` profile. Users can install it via the command line `dsh plug`