清理引用，将NavigatorServices更改为使用Message来实现导航的切换

ViewModels/ViewModelBase.cs

@@ -2,12 +2,7 @@
 
 namespace PMSWPF.ViewModels;
 
-public abstract partial class ViewModelBase:ObservableObject
+public abstract class ViewModelBase : ObservableObject
 {
-    public ViewModelBase()
-    {
-        
-    }
-    
     public abstract void OnLoaded();
 }