Add achievement system with unlock and UI popup functionality (#8)

scripts/UI/AchievementPopup.cs

@@ -0,0 +1,52 @@
+using System.Threading.Tasks;
+using Godot;
+using Mr.BrickAdventures.scripts.Resources;
+
+namespace Mr.BrickAdventures.scripts.UI;
+
+[GlobalClass]
+public partial class AchievementPopup : CanvasLayer
+{
+    [Export] public Label TitleLabel { get; set; }
+    [Export] public Label DescriptionLabel { get; set; }
+    [Export] public TextureRect IconRect { get; set; }
+    [Export] public float DisplayDuration { get; set; } = 3.0f;
+
+    private Control _container;
+    private Vector2 _startPosition;
+    private Vector2 _onScreenPosition;
+    
+    public override void _Ready()
+    {
+        _container = GetNode<Control>("Container");
+
+        _startPosition = new Vector2(_container.Position.X, -_container.Size.Y - 50);
+        _onScreenPosition = _container.Position;
+        _container.Position = _startPosition;
+    }
+    
+    public async Task ShowAchievement(AchievementResource achievement)
+    {
+        TitleLabel.Text = achievement.DisplayName;
+        DescriptionLabel.Text = achievement.Description;
+        IconRect.Texture = achievement.Icon;
+
+        var tween = CreateTween();
+        tween.TweenProperty(_container, "position", _onScreenPosition, 0.5f)
+            .SetTrans(Tween.TransitionType.Cubic)
+            .SetEase(Tween.EaseType.Out);
+        
+        await ToSignal(tween, Tween.SignalName.Finished);
+
+        await ToSignal(GetTree().CreateTimer(DisplayDuration), Timer.SignalName.Timeout);
+
+        tween = CreateTween();
+        tween.TweenProperty(_container, "position", _startPosition, 0.5f)
+            .SetTrans(Tween.TransitionType.Cubic)
+            .SetEase(Tween.EaseType.In);
+        
+        await ToSignal(tween, Tween.SignalName.Finished);
+        
+        QueueFree();
+    }
+}