dsh-balance-tasks: DeepSeek Harness Balance and Task Count Estimation Plugin

The DeepSeek Harness plugin `dsh-balance-tasks` displays the balance, peak/off-peak billing tier, and an estimated remaining task count based on historical consumption in a real-time floating card in the bottom-right corner. It supports peak/off-peak billing, data persistence, and a RESTful API. Model prices must be configured to calculate a “normalized” task count. Users can install it via a command, and it takes effect after restarting.