dsh-tui-keys: dsh-TUI Keys Quick Reference Panel

The `dsh-tui-keys` plugin is designed to address the high memorization cost caused by the numerous keybindings in dsh-TUI. It provides a full-screen shortcut reference panel via the `/keys` command, supporting search filtering, pagination, and intelligently skipping group headers. The plugin has zero dependencies, follows the system language setting for its interface, and offers complete interactive controls. It is well suited for users who operate dsh-TUI frequently, though the keybinding data is a snapshot and may vary across versions as updates are released.