dsh-fare-meter: A Taxi-Meter-Style Real-Time Billing Plugin

`dsh-fare-meter` is a DeepSeek Harness plugin designed to address the challenge of monitoring model invocation costs. It simulates a taxi fare meter and displays a real-time billing amount with five decimal places in the input box's model selection area. The plugin incorporates the official DeepSeek V4-Flash peak/off-peak pricing (with off-peak/idle usage billed at half price) and features dual calculation logic: precisely calculating settled usage and estimating in-progress output in real time based on decoding speed. The installation command is `dsh plugin --profile web add dsh-fare-meter`, helping developers intuitively track costs and achieve fine-grained control.