dsh-usage-dash: DSH Sidebar Quota Monitoring Plugin

`dsh-usage-dash` is a DeepSeek Harness (DSH) plugin designed to address the pain points of managing quotas across multiple platforms. It displays the remaining percentage for each plan via a persistent sidebar badge, and clicking the badge reveals details and reset countdowns. The plugin supports OpenCode Go, Volcano Engine, the official DeepSeek API, and custom plans, with features including automatic refreshing, tiered alerts (red ≤10%, orange ≤40%), and peak/off-peak status display. All data is stored locally to ensure security. Once installed, it provides an intuitive overview of resource consumption without requiring frequent switching between platforms.