dsh-modal-enhancer: Adding Window-Level Controls to DeepSeek Harness Modals

`dsh-modal-enhancer` is a client-side enhancement plugin for DeepSeek Harness Web, designed to address limitations in native modal interactions. By injecting styles and event listeners, it provides modals with window-level control, supporting dragging, eight-directional resizing, pinning, maximizing, background removal, and state persistence. The plugin requires no modifications to the Harness source code or rebuilding; it is directly mounted through the `dsh bundle.patch` mechanism, with state stored locally in the browser. Users can customize modal layouts, making it suitable for developers who need to move modals across multiple monitors or seek higher interaction efficiency.