dsh-win-notify: Add DeepSeek-branded Windows notifications to DSH

# Introduction When running long tasks with DeepSeek Harness (DSH), it is common to switch to other windows to attend to other matters. However, there are two critical moments when you must remain at the window: manual confirmation for tool operations and the completion of the model run. Missing the former causes the task to stall indefinitely; missing the latter leaves you unaware of when it finishes. `dsh-win-notify` aims to solve this problem by converting these two moments into Windows system notifications: a looping alarm when manual confirmation is required, and a standard notification sound when the run is complete. The following sections introduce its implementation details, installation steps, and usage notes. # What is this? `dsh-win-notify` is a Windows 11 system notification bridge plugin for DeepSeek Harness, created by li...