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/ItemInventory/Public/ItemSaveGame.h

@@ -0,0 +1,34 @@
+// Copyright ExByte Studios. Item Interaction Ecosystem.
+
+#pragma once
+
+#include "CoreMinimal.h"
+#include "GameFramework/SaveGame.h"
+#include "ItemInstanceData.h"
+#include "InventoryContainer.h"
+#include "ItemSaveGame.generated.h"
+
+/** Saved snapshot of one inventory (section 26). Only ids/state are kept. */
+USTRUCT(BlueprintType)
+struct ITEMINVENTORY_API FInventorySaveData
+{
+	GENERATED_BODY()
+
+	UPROPERTY(SaveGame)
+	TArray<FItemInstanceData> Items;
+
+	UPROPERTY(SaveGame)
+	TArray<FInventoryContainer> Containers;
+};
+
+/** SaveGame object holding any number of named inventory snapshots. */
+UCLASS()
+class ITEMINVENTORY_API UItemSaveGame : public USaveGame
+{
+	GENERATED_BODY()
+
+public:
+	/** Keyed by a stable inventory id chosen by the game (e.g. "Player0", a chest guid). */
+	UPROPERTY(SaveGame)
+	TMap<FName, FInventorySaveData> Inventories;
+};