fix(interaction): 修复Narrative Widget淡出后残留累积并解耦时长

对应 P-016 game-reviewer 审查建议（非阻塞关注项）两项：

1. [生命周期] ExecuteHideNarrative 删除 Hide() 后立即 CachedNarrativeWidget=nullptr 的那行，与 Pickup 路径对称；让 RemoveNarrativeWidget 能检测到残留 Widget 并 RemoveFromParent，修复每次交互循环视口残留实例累积。

2. [一致性] NarrativeTextWidget/PickupNotificationWidget 的 Hide() 淡出时长改为从 FadeOutAnim->GetEndTime() 读取（无动画回退 0.2f），消除与动画时长耦合的硬编码；lambda 捕获由 [this] 改为 [WeakThis](TWeakObjectPtr) 避免悬空。

补充：两个 cpp 添加 #include Animation/WidgetAnimation.h（GetEndTime 需要 UWidgetAnimation 完整类型，原仅有前向声明）。UE5.7 编译验证 Result:Succeeded，零 error/warning。

Co-Authored-By: Claude Opus 5.8 <noreply@anthropic.com>

Source/ChildHood/Interaction/PickupNotificationWidget.cpp

@@ -1,6 +1,7 @@
 // ChildHood Project - 拾取通知 UI 基类 实现
 
 #include "Interaction/PickupNotificationWidget.h"
+#include "Animation/WidgetAnimation.h"	// UWidgetAnimation 完整定义（GetEndTime 需要完整类型）
 #include "Components/TextBlock.h"
 
 void UPickupNotificationWidget::NativeOnInitialized()
@@ -36,18 +37,27 @@ void UPickupNotificationWidget::Hide()
 {
 	if (!bIsVisible) return;
 
+	// 淡出时长从 FadeOutAnim 实际时长读取，消除与动画时长耦合的硬编码
+	const float FadeOutDuration = (FadeOutAnim ? FadeOutAnim->GetEndTime() : 0.2f);
+
 	if (FadeOutAnim)
 	{
 		PlayAnimation(FadeOutAnim, 0.0f, 1, EUMGSequencePlayMode::Forward, 1.0f);
+	}
+
+	if (UWorld* World = GetWorld())
+	{
+		// 捕获弱引用避免悬空 this
+		TWeakObjectPtr<UPickupNotificationWidget> WeakThis(this);
 		FTimerHandle TempHandle;
-		if (UWorld* World = GetWorld())
+		World->GetTimerManager().SetTimer(TempHandle, [WeakThis]()
 		{
-			World->GetTimerManager().SetTimer(TempHandle, [this]()
+			if (UPickupNotificationWidget* Self = WeakThis.Get())
 			{
-				bIsVisible = false;
-				SetVisibility(ESlateVisibility::Hidden);
-			}, 0.2f, false);
-		}
+				Self->bIsVisible = false;
+				Self->SetVisibility(ESlateVisibility::Hidden);
+			}
+		}, FadeOutDuration, false);
 	}
 	else
 	{