dsh-deck-builder: Generate self-contained HTML presentations from Markdown

dsh-deck-builder is an independent community plugin for DeepSeek Harness (DSH) maintained by Blaczz and released under the MIT License. It is designed to address the need for directly displaying Markdown content (such as reports and meeting minutes) within agent tasks. By registering the `deck_build` tool, it converts Markdown into self-contained, single-file HTML presentations. The plugin features zero dependencies and requires no core modifications, with generated outputs containing inline CSS/JS and no network access. It supports three themes (`deepseek`, `light`, `dark`) and keyboard navigation (arrow key switching and fullscreen). Its splitting logic prioritizes separators such as `---`, falling back to H1/H2 headers if they are absent. Markdown rendering covers...