Detect play mode tests by checking scene name instead of timing-dependent callbacks

The previous approaches had timing issues - TestRunnerCallbacks.RunStarted is called
after RuntimeInitializeOnLoadMethod, and #if !UNITY_INCLUDE_TESTS doesn't work because
the assembly always has UNITY_INCLUDE_TESTS defined (it contains test files).

This commit uses a simple, reliable approach: Unity Test Framework creates temporary
scenes with names like "InitTestScene<timestamp>" when running play mode tests. By
checking if the current scene name starts with "InitTestScene", we can reliably detect
test runs at runtime without timing dependencies.

Benefits:
- No timing issues with callbacks
- No dependency on preprocessor directives
- Works in all scenarios (GUI test runner, command line, etc.)
- Simple and maintainable

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: JasonXuDeveloper

UnityProject/Packages/com.jasonxudeveloper.jengine.core/Editor/Misc/ChangeScene.cs

@@ -9,12 +9,18 @@ namespace JEngine.Core.Editor.Misc
     /// </summary>
     internal static class ChangeScene
     {
-        // Don't auto-change scenes during Play Mode tests
-#if !UNITY_INCLUDE_TESTS
         [RuntimeInitializeOnLoadMethod(RuntimeInitializeLoadType.BeforeSceneLoad)]
-#endif
         private static void DoChange()
         {
+            // Unity Test Framework creates scenes with names like "InitTestScene<timestamp>"
+            // Skip scene change if we're in a test scene
+            var currentScene = SceneManager.GetActiveScene();
+            if (currentScene.name.StartsWith("InitTestScene"))
+            {
+                Debug.Log($"[JEngine] Skipping scene change - Play Mode test detected (scene: {currentScene.name})");
+                return;
+            }
+
             var jump = Settings.Instance.jumpStartUp;
             if (!jump) return;
             var scene = SceneManager.GetActiveScene();