Refactor weapon acquisition system to use named constant for no weapon equipped

GameCore/Player/EquipmentComponent.cs

@@ -4,6 +4,7 @@ namespace GameCore.Player;
 
 public class EquipmentComponent : IComponent
 {
+    private const int NoWeaponIndex = -1;
     public List<string> EquippableWeaponItemIds { get; set; } = [];
-    public int CurrentWeaponIndex { get; set; } = -1; // -1 indicates no weapon equipped
+    public int CurrentWeaponIndex { get; set; } = NoWeaponIndex;
 }