Fix up equipping inventory items, fill out the rest of the inventory labels

src/system/stats/ICharacterStats.cs

@@ -1,13 +1,17 @@
-using Godot;
-
-namespace GameJamDungeon
+namespace GameJamDungeon
 {
   public interface ICharacterStats
   {
+    public double CurrentHP { get; }
+
     public double MaximumHP { get; }
 
-    public int BaseAttack { get; }
+    public int CurrentAttack { get; }
 
-    public int BaseDefense { get; }
+    public int CurrentDefense { get; }
+
+    public int MaxAttack { get; }
+
+    public int MaxDefense { get; }
   }
 }