dsh-power-launch: Desktop Launch and Safe Exit Plugin

The `dsh-power-launch` plugin for DeepSeek Harness (DSH) aims to address the cumbersome task of manually starting and stopping the Web UI on Windows. It enables one-click startup via a desktop shortcut and performs automatic version checks. It also provides a secure exit option with a second confirmation in the bottom-right corner of the Web UI, ensuring the process exits with exit code 0 to release the port. The plugin supports custom ports and mirror sources, and users should be mindful of file encoding format requirements.