Various cleanup

Zennysoft.Game.Ma/src/Components/LuckComponent.cs

@@ -1,4 +1,5 @@
 using Chickensoft.Collections;
+using System;
 using Zennysoft.Ma.Adapter;
 
 namespace Zennysoft.Game.Ma;
@@ -7,7 +8,7 @@ public class LuckComponent : ILuckComponent
 {
   public IAutoProp<int> Luck => _luck;
 
-  private AutoProp<int> _luck;
+  private readonly AutoProp<int> _luck;
   private readonly int _initialValue;
 
   public LuckComponent(int initialLuck)
@@ -22,4 +23,6 @@ public class LuckComponent : ILuckComponent
   }
 
   public void IncreaseLuck(int value) => _luck.OnNext(_luck.Value + value);
+
+  public void DecreaseLuck(int value) => _luck.OnNext(Godot.Mathf.Max(_luck.Value - value, 0));
 }