dsh-model-garden: Add a searchable, sortable, cost-aware model selector to the DSH Web UI

dsh-model-garden is a static plugin for the DeepSeek Harness (DSH) Web UI, designed to address challenges such as difficulty in searching and sorting a large number of models and the lack of cost visualization. The plugin consists of client-side `client.js` and host-side `index.js`, requiring Node.js 22+ and Web stack support. Core features include a tabular selector that provides instant search, sorting by name/context/price, favorites management, and local model filtering; integration of `models.dev` data to display prices (cached for 24 hours) and context windows; real-time display of per-task usage and costs, with support for exporting session cost details to CSV; and an inference strength selector. The plugin runs in a modular manner and does not alter the original DSH architecture; it operates solely on the Web...