Mu-scorpio/token-usage-counter: Add persistent token usage statistics to DeepSeek Harness

# Preface When using DSH (DeepSeek Harness) to run agents, token usage is the most direct cost indicator: tracking how many were used over a period, cache read/write operations, and which providers and models consumed the most requires a persistent and queryable record. DSH includes a built-in usage accumulator and usage page that suffice for basic monitoring; however, if you wish to separate the four categories of usage reported by the service provider into individual tracking, calculate daily activities locally, or access this data within your own plugins, you need an independent statistical component. The Mu-scorpio/token-usage-counter introduced below is such a plugin. # What is it Its positioning in one sentence: For D