Resolved save load issues for the nodes by chaning the unique node id to guid

Examples/Nodify.Calculator/CalculatorViewModel.cs

@@ -1,4 +1,5 @@
-using System.Diagnostics;
+using System;
+using System.Diagnostics;
 using System.IO;
 using System.Linq;
 using System.Windows;
@@ -85,7 +86,7 @@ namespace Nodify.Calculator
             Operations.WhenAdded(x =>
             {
                 x.Input.WhenRemoved(RemoveConnection);
-                if (!IsLoading) x.NodeId = (Operations.Count + 1).ToString();
+                if (!IsLoading) x.NodeId = Guid.NewGuid().ToString("N");
                 Debug.WriteLine($"Currently adding the node with node id : {x.NodeId} , Title : {x.Title}");
                 if (x is CalculatorInputOperationViewModel ci)
                 {

Examples/Nodify.Calculator/GraphSerializer.cs

@@ -16,12 +16,11 @@ namespace Nodify.Calculator
             var operations = calculator.Operations;
             var connections = calculator.Connections;
 
-            // Ensure all nodes have IDs
-            int idCounter = 1;
+            // Ensure all nodes have unique IDs
             foreach (var op in operations)
             {
                 if (string.IsNullOrEmpty(op.NodeId))
-                    op.NodeId = $"node_{idCounter++}";
+                    op.NodeId = Guid.NewGuid().ToString("N");
             }
 
             // Serialize nodes