dsh-metrics-panel: DeepSeek Harness Usage Monitoring Panel

`dsh-metrics-panel` is a monitoring dashboard plugin designed for DeepSeek Harness, addressing common developer pain points such as tracking token consumption, costs, and latency. The plugin provides features including real-time statistics, visualized trend charts, multi-dimensional aggregation, and billing configuration, with support for dark mode toggling and historical data refresh. After installing it via the CLI, users can view usage and costs across different time dimensions in the Web interface sidebar. Note that the data is stored in memory and cleared after a restart; the `dsh.bundle` declaration must be checked during installation.