dsh-voice-kit: Add voice input and audio response for DeepSeek Harness Web GUI

`dsh-voice-kit` is an MIT-licensed voice plugin for the DeepSeek Harness Web GUI, designed to enhance the interaction experience by primarily addressing the needs of voice input and reading aloud responses. The plugin supports voice input via a microphone, appending transcription results to the draft. It also supports three types of text-to-speech engines: System, Microsoft Neural, and Cloud Neural (such as SiliconFlow CosyVoice2), capable of automatically cleaning up Markdown and streaming long text in chunks. Users can configure the engine, speed, pitch, and recognition language in the settings; the key status only displays the saved state without revealing the actual values. Installation requires executing `dsh plugin add dsh-voice-kit`, followed by restarting DSH Desktop and refreshing the GUI. The plugin requires...