DeepSeek Harness Plugin: dsh-usage-stats-plus Usage and Balance Panel Enhancements

`dsh-usage-stats-plus` is DSH's official balance enhancement plugin, designed to address inaccurate local estimates. By fetching the official API in real time, applying precise billing based on peak/off-peak price schedules, and estimating consumption across all channels, it provides a usage view close to official billing. The plugin supports a Codex-style timeline, monochromatic UI, and light/dark themes, and is implemented in pure JavaScript. After installation, prices must be overridden in the configuration, and both cache billing and peak-period determination are based on Beijing time.