Enable verbose engineio logging for better WebSocket debugging

Changed engineio_logger from False to True to capture detailed WebSocket
connection, handshake, and transport-level events for troubleshooting.

https://claude.ai/code/session_01G6aE7WxjFjUUr8nkmegitZ

backend/app.py

@@ -28,7 +28,7 @@ socketio = SocketIO(
     ping_timeout=60,
     ping_interval=25,
     logger=True,
-    engineio_logger=False
+    engineio_logger=True
 )
 
 # Simple in-memory session storage (in production, use proper session management)