feat: add xAI voice bot with Grok integration

- Add pkg/xai WebSocket client for xAI Voice Agent API
- Add cmd/voicebot TeamSpeak bot with voice bridge
- Proper 20ms audio timing with buffered queue
- Clear audio queue on user interruption (VAD)

go.sum

@@ -2,5 +2,7 @@ filippo.io/edwards25519 v1.1.0 h1:FNf4tywRC1HmFuKW5xopWpigGjJKiJSV0Cqo0cJWDaA=
 filippo.io/edwards25519 v1.1.0/go.mod h1:BxyFTGdWcka3PhytdK4V28tE5sGfRvvvRV7EaN4VDT4=
 github.com/dgryski/go-quicklz v0.0.0-20151014073603-d7042a82d57e h1:MhBotBstN1h/GeA7lx7xstbFB8avummjt+nzOi2cY7Y=
 github.com/dgryski/go-quicklz v0.0.0-20151014073603-d7042a82d57e/go.mod h1:XLmYwGWgVzMPLlMmcNcWt3b5ixRabPLstWnPVEDRhzc=
+github.com/gorilla/websocket v1.5.3 h1:saDtZ6Pbx/0u+bgYQ3q96pZgCzfhKXGPqt7kZ72aNNg=
+github.com/gorilla/websocket v1.5.3/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
 gopkg.in/hraban/opus.v2 v2.0.0-20230925203106-0188a62cb302 h1:xeVptzkP8BuJhoIjNizd2bRHfq9KB9HfOLZu90T04XM=
 gopkg.in/hraban/opus.v2 v2.0.0-20230925203106-0188a62cb302/go.mod h1:/L5E7a21VWl8DeuCPKxQBdVG5cy+L0MRZ08B1wnqt7g=