Add initial game systems and input handling for player interactions

Assets/Scripts/Core/Systems/LivesSystem.cs

@@ -0,0 +1,35 @@
+using System;
+
+namespace Core.Systems
+{
+    public class LivesSystem : IDisposable
+    {
+        private int _currentLives;
+
+        public LivesSystem(int initialLives)
+        {
+            _currentLives = initialLives;
+            GameEvents.PresentDropped += OnPresentDropped;
+            
+            GameEvents.ReportLivesUpdated(_currentLives);
+        }
+
+        private void OnPresentDropped()
+        {
+            if (_currentLives <= 0) return;
+            
+            _currentLives--;
+            GameEvents.ReportLivesUpdated(_currentLives);
+            
+            if (_currentLives <= 0)
+            {
+                GameEvents.ReportGameOver();
+            }
+        }
+
+        public void Dispose()
+        {
+            GameEvents.PresentDropped -= OnPresentDropped;
+        }
+    }
+}