(Feat) Add build cost

Assets/GAME/Script/Player/Events/PlayerEvents.cs

@@ -1,7 +1,9 @@
 using System;
+using System.Collections.Generic;
 using System.Diagnostics;
 using UnityEngine;
 using Ashwild.Audio;
+using Ashwild.Building;
 using Ashwild.Harvesting;
 using Ashwild.Interaction;
 using Ashwild.Inventory;
@@ -135,6 +137,7 @@ namespace Ashwild.Player
         public static event Action<bool> BuildMenuOpenChanged;  // the construction menu opened (true) or closed (false)
         public static event Action<bool> BuildPlacingChanged;   // a build ghost started (true) / stopped (false) being positioned
         public static event Action<bool> DemolishModeChanged;   // the hammer entered (true) / left (false) demolition mode (right-click held)
+        public static event Action<IReadOnlyList<BuildCostView>> BuildCostChanged; // the active build's cost to display near the crosshair (null/empty = clear)
 
         // ============================================================
         // Cooking events
@@ -305,6 +308,17 @@ namespace Ashwild.Player
             BuildPlacingChanged?.Invoke(placing);
         }
 
+        /// <summary>
+        /// Publishes the active build's cost lines for the crosshair to render (or a null/empty list to
+        /// clear it). Owner-side only; BuildManager re-raises it live as the inventory changes so the
+        /// affordability colouring stays current while a piece is being positioned.
+        /// </summary>
+        public static void RaiseBuildCostChanged(IReadOnlyList<BuildCostView> cost)
+        {
+            Log(nameof(BuildCostChanged));
+            BuildCostChanged?.Invoke(cost);
+        }
+
         /// <summary>
         /// Toggles demolition mode (right-click held with the hammer out). Owner-side only; the
         /// hammer raises it and BuildManager drives the world-facing targeting/destroy from it.