dsh-plugin-dosage: Centrally view balance and peak-valley costs in DSH sidebar

`dsh-plugin-dosage` is a community plugin for DeepSeek Harness (DSH) designed to address the issues of scattered billing entry points and multi-vendor account monitoring. The plugin provides a unified sidebar `Usage/Balance` popup within the DSH Web configuration file, centrally displaying the balance and account status, Token statistics, and the cost per call calculated based on peak and valley periods for multiple providers (such as DeepSeek, OpenRouter, Moonshot, etc.). Core features include an overview panel showing total expenditure and peak/valley splits; a monthly heatmap supporting history views by cost or Token; and detailed call logs recording models, hit rates, and fees, offering various time filters. The plugin supports CSV, JSON, PNG data export and time-based...