dsh-usage-plugin: Record Token Usage and Costs for Each Call in DSH

dsh-usage-plugin is a DeepSeek Harness client plugin maintained by feiyang-dev that provides usage and cost tracking, along with balance inquiry panels, within the Web UI. It records token usage and cache hits for each model invocation, calculates costs based on DeepSeek's peak and off-peak pricing, and supports usage calendars, price table editing, CSV/JSON/PNG export, and local persistence. It can be installed via one-click setup on the desktop client or by executing the command `dsh plugin --profile web add @feiyang666/dsh-usage-plugin`. This plugin is ideal for DSH users who need to track token consumption, distinguish between peak and off-peak costs, and check account balances.