Add action gathering functionality: implement ActionGathered model and repository, update Pet model and services, and enhance GameItemsRepository with item retrieval methods.

Services/PetInventoryService.cs

@@ -146,6 +146,12 @@ namespace PetCompanion.Services
             if (gameItem == null)
                 throw new Exception("Item not found");
 
+            if (pet == null)
+                throw new Exception("Pet not found");
+
+            if (pet.Inventory.Items.Count + quantity > pet.Inventory.Capacity)
+                throw new Exception("Not enough space in inventory");
+
             for (int i = 0; i < quantity; i++)
             {
                 pet.Inventory.Items.Add(itemId);