dsh-outline: Real-time session outline for DSH Web GUI

dsh-outline is a DSH client plugin maintained by urzeye, offering a real-time outline tree on the Web GUI session page. It uses user questions as primary nodes and Markdown headings from assistant responses as sub-nodes, updating synchronously during streaming generation and allowing navigation to the corresponding content upon clicking. The plugin supports level control, search and favorites, a floating panel, and theme internationalization. The installation command is `dsh plugin --profile web add dsh-outline@latest`, and a restart of dsh web is required after installation. Licensed under MIT, its interactive design is ported from Ophel.