dsh-sqy-rewind: Rewind a DSH session to a specified turn

dsh-sqy-rewind is a DeepSeek Harness plugin designed to address the need to undo specific conversation turns. It supports rewinding the current session to a point before a designated turn by masking surfaces and hiding DOM nodes; this operation is irreversible. The plugin provides CLI-based installation, API calls, and UI button operations, supports automatically stopping a running conversation, and depends on turnOutline projection.