Implement inventory system with item management and pickup functionality

GameCore/Inventory/PickupSystem.cs

@@ -0,0 +1,36 @@
+using GameCore.Combat;
+using GameCore.ECS;
+using GameCore.ECS.Interfaces;
+using GameCore.Events;
+using GameCore.Physics;
+using GameCore.Player;
+
+namespace GameCore.Inventory;
+
+public class PickupSystem : ISystem
+{
+    public void Update(World world, float deltaTime)
+    {
+        var entitiesWithCollisions = world.GetEntitiesWith<CollisionEventComponent>();
+        var withCollisions = entitiesWithCollisions.ToList();
+        foreach (var entity in withCollisions)
+        {
+            if (world.GetComponent<PlayerComponent>(entity) == null) return;
+
+            var collision = world.GetComponent<CollisionEventComponent>(entity);
+            if (collision == null) continue;
+
+            var pickup = world.GetComponent<PickupComponent>(entity);
+            var inventory = world.GetComponent<InventoryComponent>(entity);
+
+            if (pickup == null || inventory == null) continue;
+
+            var item = new Item(pickup.ItemId, pickup.Quantity);
+            // In the future, handle IsInstantUse items here
+            world.PublishEvent(new AddItemToInventoryEvent(entity, item));
+            world.AddComponent(collision.OtherEntity, new DeathComponent());
+        }
+
+        foreach (var entity in withCollisions) world.RemoveComponent<CollisionEventComponent>(entity);
+    }
+}