Initial commit: Item Interaction Ecosystem plugin (UE5.7)

Server-authoritative, data-driven item/inventory/interaction/carry/equipment/
world-slot/placement/crafting framework. 8 modules, compiles against UE 5.7.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Source/ItemCore/Public/ItemLockData.h

@@ -0,0 +1,42 @@
+// Copyright ExByte Studios. Item Interaction Ecosystem.
+
+#pragma once
+
+#include "CoreMinimal.h"
+#include "GameplayTagContainer.h"
+#include "ItemLockData.generated.h"
+
+/**
+ * Server-side soft lock placed on an item while a transaction owns it (section 20).
+ * Prevents dupes / conflicts: a locked item cannot be moved, taken, dropped,
+ * crafted, deleted or stacked by anyone but the locking actor.
+ */
+USTRUCT(BlueprintType)
+struct ITEMCORE_API FItemLockData
+{
+	GENERATED_BODY()
+
+	UPROPERTY(BlueprintReadOnly, Category = "Item|Lock")
+	bool bLocked = false;
+
+	/** Lock.Carrying / Lock.Using / Lock.Transferring / ... */
+	UPROPERTY(BlueprintReadOnly, Category = "Item|Lock")
+	FGameplayTag LockReason;
+
+	UPROPERTY(BlueprintReadOnly, Category = "Item|Lock")
+	TWeakObjectPtr<AActor> LockedBy;
+
+	/** Server world time (seconds) at which the lock auto-expires; 0 = no expiry. */
+	UPROPERTY(BlueprintReadOnly, Category = "Item|Lock")
+	float LockExpireTime = 0.f;
+
+	bool IsLockedBy(const AActor* Actor) const { return bLocked && LockedBy.Get() == Actor; }
+
+	void Clear()
+	{
+		bLocked = false;
+		LockReason = FGameplayTag();
+		LockedBy = nullptr;
+		LockExpireTime = 0.f;
+	}
+};