dsh-deepseek-usage-monitor: DeepSeek Harness Token Usage and Balance Monitoring Plugin

`dsh-deepseek-usage-monitor` is a local plugin designed specifically for DeepSeek Harness (DSH) to address pain points in API token consumption and balance tracking. Its core features include host-side event listening to automatically record token usage (with support for multi-model grouping and cache statistics), scheduled background polling of DeepSeek's official API to retrieve balance information, and real-time visualization via a floating card in the bottom-right corner of the Web interface. The plugin supports drag-to-adjust positioning, collapsing and expanding, forced refresh, persistent data storage, and does not log sensitive conversation content, making it suitable for fine-grained local management of API costs.