dsh-voice: DSH TTS and STT Plugin

dsh-voice is a voice processing plugin based on the DSH framework, designed to provide simplified TTS (Text-to-Speech) and STT (Speech-to-Text) capabilities for agents. The plugin adopts the MIT license, requires Node.js version 22 or above, has no runtime dependency on internal modules, and implements communication via native WebSockets. Its core functions consist of three tools: `voice_tts` supports free synthesis of text into MP3 files, allows customization of parameters such as voice timbre and speed, and can be used with zero configuration; `voice_stt` is used for audio-to-text transcription, supports OpenAI-compatible interfaces, and requires configuration of an ASR key (recommended to be managed via environment variables); and `voice_list` is used to query the list of available voices. The plugin is accessed via `dsh plug...