Add attribute system with core stats and gameplay components

GameCore/Attributes/AttributeComponent.cs

@@ -0,0 +1,42 @@
+using GameCore.ECS.Interfaces;
+
+namespace GameCore.Attributes;
+
+/// <summary>
+///     A component that stores all gameplay-relevant stats for an entity.
+///     This design is adapted directly from the excellent CharacterAttributes class
+///     in the 'broberry' project. It's a flexible, data-driven way to manage stats.
+/// </summary>
+public class AttributeComponent : IComponent
+{
+    public readonly Dictionary<Attribute, float> BaseValues = new();
+    public readonly Dictionary<Attribute, float> CurrentValues = new();
+
+    public event Action<Attribute, float>? OnAttributeChanged;
+
+    public void SetBaseValue(Attribute attr, float value)
+    {
+        BaseValues[attr] = value;
+        SetCurrentValue(attr, value);
+    }
+
+    public float GetValue(Attribute attr)
+    {
+        return CurrentValues.GetValueOrDefault(attr, 0f);
+    }
+
+    public void ModifyValue(Attribute attr, float delta)
+    {
+        var newValue = GetValue(attr) + delta;
+        SetCurrentValue(attr, newValue);
+    }
+
+    public void SetCurrentValue(Attribute attr, float value, bool force = false)
+    {
+        if (CurrentValues.TryGetValue(attr, out var oldValue) && !(System.Math.Abs(oldValue - value) > 0.001f) &&
+            !force) return;
+
+        CurrentValues[attr] = value;
+        OnAttributeChanged?.Invoke(attr, value);
+    }
+}