dsh-usage-display: Displaying Model Provider Balances and Usage in the DeepSeek Harness Web Interface

`dsh-usage-display` is a session header usage monitoring plugin that runs in the DSH Web interface. It addresses the tendency for API balance monitoring to be overlooked by using the Host process to fetch and cache data from official APIs, while API keys remain on the server for security. The plugin supports DeepSeek, MiniMax, and Zhipu GLM, and provides multi-dimensional metrics display, alert thresholds, progress visualization, and fault isolation. Users can hot-update configurations on the settings page to monitor quotas and balances in real time.