dsh-open-with: Open a DeepSeek Harness Workspace in a Local Editor

`dsh-open-with` is a client plugin for DeepSeek Harness designed to connect the Web interface with local development environments, allowing registered workspaces to be opened directly in detected local editors. The plugin supports automatic detection of multiple editors, custom configuration, and dynamic refresh, and strictly adheres to security boundaries by transmitting only editor state and not uploading files. It requires DSH 0.1.0-rc.5 or higher, and can be enabled by adding it via the configuration file and restarting the service.