dsh-echarts: Let DSH Responses Include Interactive Charts

`dsh-echarts` is a dedicated plugin for DeepSeek Web, designed to directly render the `echarts` code output by the model into interactive charts. It requires no additional Tool calls, supports interactions such as tooltips, zooming, and exporting, and adapts to light and dark themes. After installation via `npx`, the model only needs to output an ECharts configuration in Strict JSON format within a fenced code block to generate charts, making it suitable for data analysis, operations reporting, and trend visualization.