dsh-usage-lens: DeepSeek Harness Web UI Usage Statistics Panel

`dsh-usage-lens` is a DeepSeek Harness (DSH) Web UI plugin developed by yokesky, designed to provide intuitive local usage statistics functionality. Upon installation, it adds a "Usage Statistics" page to the DSH settings panel, displaying core data such as token usage, the number of sessions and messages, active days, consecutive days, and the most used models. The plugin includes a GitHub-style 280-day activity heatmap, a daily token consumption trend chart that can switch perspectives between models and vendors, and a dual-ring pie chart supporting three modes: summary, vendor, and model, automatically adapting to DSH's light and dark themes. Users can install it via npm (`dsh plugin --profile web add @yokesky/dsh-us...`)