Add event publishing for inventory and combat interactions

GameCore/Events/ProjectileImpactEvent.cs

@@ -0,0 +1,10 @@
+using GameCore.ECS;
+using GameCore.Events.Interfaces;
+
+namespace GameCore.Events;
+
+public readonly struct ProjectileImpactEvent(Entity projectile, HitResult hit) : IEvent
+{
+    public readonly Entity ProjectileEntity = projectile;
+    public readonly HitResult Hit = hit;
+}