dsh-ui-enhancements: UI Enhancement Plugin for DeepSeek Harness

`dsh-ui-enhancements` is a UI enhancement plugin for DeepSeek Harness (DSH), designed to optimize session management and workspace operations. Key features include: support for standalone conversations in “no-workspace” mode; automatic sidebar workspace sorting by last update time, with manual drag-and-drop sorting; a global plugin toggle that is locked on by default for system protection; a conversation list with hover-based quick pinning, archiving, and immediate deletion; and a new entry for managing archived conversations, with support for restoring and deleting them, along with improved loading performance. The plugin requires DSH version 0.1.5-rc.1 and the JSONL backend.