DSH desktop client

Key features

• Uses a random free loopback port instead of assuming port 3080 is available.
• Shows immediate, stage-based startup progress while the local Harness becomes ready.
• Starts and stops the Harness server together with the desktop application.
• Provides a direct Plugins menu with online catalog search and npm/GitHub installation.
• Opens conversation files in VS Code, Cursor, VSCodium, or Zed, with workspace actions in the sidebar, session header, and native menu.