Big refactor in place: Organize nodes in line with dependency injection expectations, use state machine flow more

src/ui/pause_menu/PauseMenu.cs

@@ -0,0 +1,23 @@
+using Chickensoft.AutoInject;
+using Chickensoft.GodotNodeInterfaces;
+using Chickensoft.Introspection;
+using Godot;
+using System;
+
+public interface IPauseMenu : IControl
+{
+  void FadeIn();
+  void FadeOut();
+}
+
+[Meta(typeof(IAutoNode))]
+public partial class PauseMenu : Control, IPauseMenu
+{
+  public override void _Notification(int what) => this.Notify(what);
+
+  [Node] public IAnimationPlayer AnimationPlayer { get; set; } = default!;
+
+  public void FadeIn() => AnimationPlayer.Play("fade_in");
+
+  public void FadeOut() => AnimationPlayer.Play("fade_out");
+}