feat: Add Create Network Config button in Inspector

- Custom Editor shows button when NetworkConfig is null
- Clicking creates and assigns a new NetworkConfig asset
- Shows info box explaining the purpose of NetworkConfig
- Better onboarding experience for new users

Author: SamuelGuizani

Assets/CasperSDK/Samples/CasperWalletDemo/Editor.meta

@@ -0,0 +1,79 @@
+using UnityEngine;
+using UnityEditor;
+using CasperSDK.Core.Configuration;
+
+namespace CasperSDK.Samples.Editor
+{
+    /// <summary>
+    /// Custom Editor for CasperWalletDemoController.
+    /// Shows a "Create Network Config" button when the field is empty.
+    /// </summary>
+    [CustomEditor(typeof(CasperWalletDemoController))]
+    public class CasperWalletDemoControllerEditor : UnityEditor.Editor
+    {
+        private SerializedProperty _networkConfigProp;
+
+        private void OnEnable()
+        {
+            _networkConfigProp = serializedObject.FindProperty("_networkConfig");
+        }
+
+        public override void OnInspectorGUI()
+        {
+            serializedObject.Update();
+
+            // Draw the NetworkConfig field
+            EditorGUILayout.PropertyField(_networkConfigProp);
+
+            // If NetworkConfig is null, show helper button
+            if (_networkConfigProp.objectReferenceValue == null)
+            {
+                EditorGUILayout.HelpBox(
+                    "No Network Config assigned. Using Testnet defaults.\n" +
+                    "Create one to customize network settings (Mainnet, custom RPC, etc.)",
+                    MessageType.Info);
+
+                EditorGUILayout.BeginHorizontal();
+                GUILayout.FlexibleSpace();
+                
+                if (GUILayout.Button("Create Network Config", GUILayout.Width(180)))
+                {
+                    CreateAndAssignNetworkConfig();
+                }
+                
+                EditorGUILayout.EndHorizontal();
+            }
+
+            serializedObject.ApplyModifiedProperties();
+        }
+
+        private void CreateAndAssignNetworkConfig()
+        {
+            // Create the NetworkConfig asset
+            var config = ScriptableObject.CreateInstance<NetworkConfig>();
+            
+            // Determine save path
+            var path = EditorUtility.SaveFilePanelInProject(
+                "Save Network Config",
+                "NetworkConfig",
+                "asset",
+                "Choose where to save the Network Config");
+
+            if (string.IsNullOrEmpty(path))
+                return;
+
+            // Save and assign
+            AssetDatabase.CreateAsset(config, path);
+            AssetDatabase.SaveAssets();
+            
+            _networkConfigProp.objectReferenceValue = config;
+            serializedObject.ApplyModifiedProperties();
+            
+            // Select the new asset
+            Selection.activeObject = config;
+            EditorGUIUtility.PingObject(config);
+            
+            Debug.Log($"[CasperSDK] NetworkConfig created at: {path}");
+        }
+    }
+}