dsh-timesheet: DeepSeek Harness Session Log Time Statistics Plugin

`dsh-timesheet` is a DeepSeek Harness (DSH) client plugin that fills a gap in wall-clock time statistics across the ecosystem. It extracts turn-level data from session logs and aggregates metrics such as total elapsed time, failure rate, and first-token latency by day, project, provider, and source. The plugin supports both Markdown and JSON output, can be used via a command-line tool, and can also be invoked directly from an Agent. It is inherently read-only and well suited for developers to analyze agent efficiency, but note that it only supports parsing plain-text logs and requires Node.js to be installed.