fix: incorrect receiver and incorrect belief

ref: N25B-300

src/control_backend/agents/bdi/bdi_core_agent/bdi_core_agent.py

@@ -83,7 +83,7 @@ class BDICoreAgent(BaseAgent):
             self._add_belief(belief_name, args)
 
             if belief_name == "user_said":
-                self._add_belief("user_said")
+                self._add_belief("new_message")
 
     def _add_belief(self, belief_name: str, arguments: Iterable[str] = []):
         args = (agentspeak.Literal(arg) for arg in arguments)