消除所有错误，重新构建

DMS.Core/Models/VariableMqtt.cs

@@ -0,0 +1,10 @@
+using DMS.Core.Models;
+
+namespace DMS.Core.Models;
+
+public class VariableMqtt
+{
+    public Variable Variable { get; set; }
+    public MqttServer Mqtt { get; set; }
+    public int MqttId { get; set; }
+}