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/main.py

@@ -1,10 +1,5 @@
 from __future__ import annotations
 
-import os
-
-os.environ["MEDIAPIPE_DISABLE_LOGGING"] = "1"
-os.environ["GLOG_minloglevel"] = "3"
-
 import asyncio
 
 from loguru import logger
@@ -16,8 +11,14 @@ from app.signaling.websocket_server import main as serve
 def main():
     startup()
     logger.info("Starting server...")
-    asyncio.run(serve())
+    try:
+        asyncio.run(serve())
+    except (KeyboardInterrupt, SystemExit):
+        logger.info("Server stopped by user")
+    except Exception as e:
+        logger.error(f"Server error: {e}")
+        raise
 
 
 if __name__ == "__main__":
-    main()
+    main()