Add DamageNumberManager and DamageNumber for displaying damage feedback

Autoloads/DamageNumberManager.cs

@@ -0,0 +1,56 @@
+using System.Collections.Generic;
+using Godot;
+using Mr.BrickAdventures.scripts.components;
+using Mr.BrickAdventures.scripts.UI;
+
+namespace Mr.BrickAdventures.Autoloads;
+
+public partial class DamageNumberManager : Node
+{
+    [Export] public PackedScene DamageNumberScene { get; set; }
+    
+    private readonly List<Node> _managedNodes = [];
+    
+    public void Register(Node node)
+    {
+        if (_managedNodes.Contains(node)) return;
+        
+        var healthComponent = node.GetNodeOrNull<HealthComponent>("HealthComponent");
+        if (healthComponent == null)
+        {
+            GD.PrintErr($"Node '{node.Name}' tried to register with DamageNumberManager but has no HealthComponent.");
+            return;
+        }
+
+        healthComponent.HealthChanged += (delta, total) => OnHealthChanged(healthComponent, delta);
+        node.TreeExiting += () => Unregister(node);
+        _managedNodes.Add(node);
+    }
+    
+    public void Unregister(Node node)
+    {
+        var healthComponent = node.GetNodeOrNull<HealthComponent>("HealthComponent");
+        if (healthComponent != null)
+        {
+            healthComponent.HealthChanged -= (delta, _) => OnHealthChanged(healthComponent, delta);
+        }
+        _managedNodes.Remove(node);
+    }
+
+    private void OnHealthChanged(HealthComponent healthComponent, float delta)
+    {
+        if (delta >= 0) return;
+        
+        if (DamageNumberScene == null)
+        {
+            GD.PrintErr("DamageNumberManager: DamageNumberScene is not set!");
+            return;
+        }
+        
+        var damageNumber = DamageNumberScene.Instantiate<DamageNumber>();
+        GetTree().CurrentScene.AddChild(damageNumber);
+        
+        var position = healthComponent.GlobalPosition;
+        damageNumber.ShowDamage(Mathf.Abs(delta), position);
+    }
+}