dsh-user-question-nav: Conversation Navigation Plugin

The `dsh-user-question-nav` plugin aims to address the challenge of quickly locating user questions in long DeepSeek Harness conversations. It provides a capsule track and an edge-attached drawer on the right side of the chat area, supporting question list display after hovering for one second, keyword search, and smooth navigation. The plugin includes mechanisms such as boundary bubble prompts, automatic position calibration, and session remounting to ensure stability in complex layouts. Installation must be performed via terminal commands and requires the DeepSeek Harness Desktop environment.