Add attribute system with core stats and gameplay components

GameCore/Combat/ProjectileCleanupSystem.cs

@@ -0,0 +1,25 @@
+using GameCore.ECS;
+using GameCore.ECS.Interfaces;
+using GameCore.Physics;
+
+namespace GameCore.Combat;
+
+public class ProjectileCleanupSystem : ISystem
+{
+    public void Update(World world, float deltaTime)
+    {
+        var projectiles = world.GetEntitiesWith<ProjectileComponent>();
+        foreach (var projectile in projectiles)
+        {
+            var projectileData = world.GetComponent<ProjectileComponent>(projectile);
+            var position = world.GetComponent<PositionComponent>(projectile);
+            var velocity = world.GetComponent<VelocityComponent>(projectile);
+
+            if (projectileData == null || position == null || velocity == null)
+                continue;
+
+            projectileData.Lifetime -= deltaTime;
+            if (projectileData.Lifetime <= 0f) world.AddComponent(projectile, new DeathComponent());
+        }
+    }
+}