refactor: standardization round 2

- ConsoleManager: lazy GameManager/AchievementManager via Instance (fixes NullRef on console commands)
- AchievementManager, GhostManager: add static Instance property
- GhostEventHandler: use GhostManager.Instance, add _ExitTree unsubscription
- SpeedRunManager: remove unused IsVisible guard; TimeUpdated now emits when running
- SpeedRunHud: use SpeedRunManager.Instance, remove dead IsVisible binding
- SaveDataDto: moved to scripts/State/SaveDataDto.cs
- GameManager.AddCoins: XML doc clarifying permanent vs session coins

Autoloads/GhostManager.cs

@@ -7,8 +7,13 @@ namespace Mr.BrickAdventures.Autoloads;
 
 public partial class GhostManager : Node
 {
+    public static GhostManager Instance { get; private set; }
+
     [Export] private PackedScene GhostPlayerScene { get; set; }
-    
+
+    public override void _Ready() => Instance = this;
+    public override void _ExitTree() { if (Instance == this) Instance = null; }
+
     public bool IsRecording { get; private set; } = false;
     public bool IsPlaybackEnabled { get; private set; } = true;