feat: 语音流式输入管线 + VAD前端集成 + 插件-工具合并清理

- 前端: VAD语音检测(@ricky0123/vad-web) + useVoiceInput双模式(流式WS/REST)
- Gateway: VoiceStreamManager代理WS流式STT到voice-service
- Voice-service: DashScope REST → Realtime WS → Whisper三级引擎 + ffmpeg转码
- 共享模块: pkg/audio(音频转换) + pkg/dashscope(ASR REST客户端)
- 清理: 移除旧plugin-manager和pkg/plugins，完成插件→工具合并
- 文档: 完善gateway-api.md和voice-service.md语音API文档
- 工具: scripts/voice/ 语音转换脚本集

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend/voice-service/go.mod

@@ -2,9 +2,15 @@ module git.yeij.top/AskaEth/Cyrene/voice-service
 
 go 1.26.2
 
-replace git.yeij.top/AskaEth/Cyrene/pkg/logger => ../pkg/logger
+replace (
+	git.yeij.top/AskaEth/Cyrene/pkg/logger => ../pkg/logger
+	git.yeij.top/AskaEth/Cyrene/pkg/audio => ../pkg/audio
+	git.yeij.top/AskaEth/Cyrene/pkg/dashscope => ../pkg/dashscope
+)
 
 require (
 	github.com/gorilla/websocket v1.5.3
+	git.yeij.top/AskaEth/Cyrene/pkg/audio v0.0.0
+	git.yeij.top/AskaEth/Cyrene/pkg/dashscope v0.0.0
 	git.yeij.top/AskaEth/Cyrene/pkg/logger v0.0.0
 )