Fix compilation errors from command receiver removal

- Remove AgentCommand import from agent.rs
- Remove handle_commands() method
- Remove command handling from main loop
- Remove command_port validation checks

agent/src/config/validation.rs

@@ -7,14 +7,6 @@ pub fn validate_config(config: &AgentConfig) -> Result<()> {
         bail!("ZMQ publisher port cannot be 0");
     }
 
-    if config.zmq.command_port == 0 {
-        bail!("ZMQ command port cannot be 0");
-    }
-
-    if config.zmq.publisher_port == config.zmq.command_port {
-        bail!("ZMQ publisher and command ports cannot be the same");
-    }
-
     if config.zmq.bind_address.is_empty() {
         bail!("ZMQ bind address cannot be empty");
     }