fix(ui): 修复UI过渡流水线中的空引用异常

- 添加空值检查避免FromUiKey为null时的日志记录错误
- 确保流水线执行时参数安全处理

GFramework.Game/ui/UiTransitionPipeline.cs

@@ -110,7 +110,7 @@ public class UiTransitionPipeline
         Log.Debug(
             "Execute pipeline: Phases={0}, From={1}, To={2}, Type={3}, HandlerCount={4}",
             phases,
-            @event.FromUiKey,
+            @event.FromUiKey ?? "None",
             @event.ToUiKey ?? "None",
             @event.TransitionType,
             _handlers.Count