Integrate product-ws voice demo on port 8000 alongside REST API.

Add src/voice Pipecat pipeline, browser demo at /voice-demo, and config/voice.json.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/main.py

@@ -1,8 +1,8 @@
 from fastapi import FastAPI
-import sys
 from .api.endpoints import router as api_router
 from .core.fastgpt_client import lifespan
 from .core.logging_config import setup_logging
+from .voice.routes import register_voice
 
 # Setup logging first
 setup_logging()
@@ -18,4 +18,5 @@ app = FastAPI(
 def read_root():
     return {"message": "Server is running."}
 
-app.include_router(api_router)
+app.include_router(api_router)
+register_voice(app)