Parse config.yaml into typed AppConfig dataclass

- ServerConfig, VideoConfig, ModelConfig, DeadBugConfig,
  AudioConfig, LoggingConfig as nested dataclasses
- Consumers use config.server.host, config.model.resolved_path etc.
- env var overrides preserved via _apply_env_overrides()

app/signaling/websocket_server.py

@@ -7,7 +7,7 @@ import websockets
 from loguru import logger
 
 from app.webrtc.peer_session import PeerSession
-from configs.load import WS_HOST, WS_MAX_SIZE, WS_PORT
+from configs.load import config
 
 
 async def handle_client(websocket):
@@ -21,6 +21,7 @@ async def handle_client(websocket):
 
 
 async def main():
-    logger.info(f"WebRTC signaling server: ws://{WS_HOST}:{WS_PORT}")
-    async with websockets.serve(handle_client, WS_HOST, WS_PORT, max_size=WS_MAX_SIZE):
+    cfg = config.server
+    logger.info(f"WebRTC signaling server: ws://{cfg.host}:{cfg.port}")
+    async with websockets.serve(handle_client, cfg.host, cfg.port, max_size=cfg.max_ws_size):
         await asyncio.Future()