dsh-tool-fold: Collapse All Tool Call Cards and Thinking Blocks in a DSH Conversation into a Single Toggle

The `dsh-tool-fold` plugin is designed to address the visual clutter caused by numerous tool calls and thinking blocks in DeepSeek Harness debugging scenarios. It provides a “Maximum Fold” mode that hides all processing content by default, retaining only user messages and assistant replies for a clean view. Core features include a global one-click toggle to show or hide content, persistent state saving, and automatic adaptation to streaming. When the toggle is enabled, the content is highlighted in brand blue to distinguish the processing flow. Users can enable this pure client-side plugin with a simple installation command (`dsh plugin --profile web add`) to flexibly switch between “Pure mode” and “Debug mode”.