dsh-conversation-shortcuts: Add Conversation Shortcuts to the WebUI

dsh-conversation-shortcuts is a keyboard shortcuts plugin for DeepSeek Harness (DSH), designed to reduce reliance on the mouse and improve the efficiency of managing multiple conversations. Its core features include creating new conversations, toggling the sidebar, opening settings, and quickly jumping to a conversation in the list using number keys. To install it, add the plugin via the command line and reload the WebUI. This plugin is suitable for scenarios that require frequent keyboard use, but note that some shortcuts (such as ⌘1~9) may be intercepted in Chromium-based browsers.