Initial Combat Implementation

Assets/_Project/Scripts/Simulation/Combat/HitRadius.cs

@@ -0,0 +1,15 @@
+using Unity.Entities;
+
+namespace ProjectM.Simulation
+{
+    /// <summary>
+    /// Hit-test radius (world units) for a damageable entity. Baked identically on client and server
+    /// from authoring so projectile collision is deterministic; consumed server-side by
+    /// ProjectileDamageSystem to decide whether a projectile struck this entity. Not replicated.
+    /// </summary>
+    public struct HitRadius : IComponentData
+    {
+        /// <summary>Collision radius in world units; the projectile hit test compares planar (XZ) distance against this.</summary>
+        public float Value;
+    }
+}