Implement health modification on enemy kill; add HealOnKillModifier and update death behavior

Assets/Scripts/Systems/Health.cs

@@ -7,16 +7,21 @@ namespace Systems
 {
     public class Health : MonoBehaviour
     {
+        private GameObject lastAttacker;
+        
         [Self, SerializeField] private Character character;
         [SerializeField] private float initialHealth = 100f;
+        
+        public GameObject LastAttacker => lastAttacker;
 
         private void Start()
         {
             character.attributes.SetHealth(initialHealth);
         }
 
-        public void TakeDamage(float damage)
+        public void TakeDamage(float damage, GameObject attacker = null)
         {
+            lastAttacker = attacker;
             var effectiveDamage = Math.Max(damage - character.attributes.Armor, 1);
             character.attributes.ModifyHealth(-effectiveDamage);
         }