dsh-env-switcher: A Plugin for Switching Between Windows and WSL2 DSH Instances

The `dsh-env-switcher` plugin is designed to address the cumbersome switching process when maintaining DeepSeek Harness (DSH) instances across both Windows and WSL2 environments. It allows users to switch directly via the "Runtime Environment" tab in the Web UI, eliminating the need to manually copy and paste URLs. The plugin supports coexistence mode (with default ports 3080 and 3081) and features such as sidebar-collapse awareness and independent session history. Users can install it via the official command or from source, and configure the port and path in `cordis.patch.yml`. After installation, restart the server to start using it.