fix: Correct DemoSceneCreator save path and remove duplicate scene

- Scene now saves to Samples/CasperWalletDemo/CasperWalletDemo.unity
- Removed old duplicate from Samples/ root
- Ensures correct scene is deployed to UPM package

Author: SamuelGuizani

Assets/CasperSDK/Editor/DemoSceneCreator.cs

@@ -61,7 +61,7 @@ public static void CreateDemoScene()
             CreateDemoController(canvasGO);
 
             // Save scene
-            var scenePath = "Assets/CasperSDK/Samples/CasperWalletDemo.unity";
+            var scenePath = "Assets/CasperSDK/Samples/CasperWalletDemo/CasperWalletDemo.unity";
             EditorSceneManager.SaveScene(scene, scenePath);
 
             Debug.Log($"[CasperSDK] Demo scene created at: {scenePath}");