chore: adjust message/command structure and write unit tests

ref: N25B-205

src/control_backend/agents/ri_command_agent.py

@@ -6,7 +6,7 @@ import zmq
 
 from control_backend.core.config import settings
 from control_backend.core.zmq_context import context
-from control_backend.schemas.message import Message
+from control_backend.schemas.ri_message import SpeechCommand
 
 logger = logging.getLogger(__name__)
 
@@ -33,9 +33,8 @@ class RICommandAgent(Agent):
             # Try to get body
             try:
                 message_json = json.loads(body.decode("utf-8"))
-                message = Message.model_validate(message_json)
-                logger.info("Received message \"%s\"", message.message)
-
+                message = SpeechCommand.model_validate(message_json)
+            
                 # Send to the robot.
                 await self.agent.pubsocket.send_json(message)
             except Exception as e: