cc-dsh-notifier: Windows Notification and Session Jump Plugin

`cc-dsh-notifier` is a notification plugin developed specifically for DeepSeek Harness (DSH) on Windows, designed to address the frequent window switching required in multi-session development. The plugin uses the native Windows Toast system to notify users when an agent requires their intervention, with a single click to jump directly back to the corresponding session window. It adopts a hybrid Node.js and Python architecture, requires no extra dependencies, and supports multi-session management and localization. Installation requires Node.js 18+, Python 3, and the `winrt-runtime` environment, and can be installed uniformly through the `dsh plugin` command. The tool is compatible with DSH 0.1.0-rc.6 and is open-sourced under the MIT License.