refactor: enhance GameStateStore integration and improve skill management

scripts/State/SessionState.cs

@@ -9,11 +9,6 @@ namespace Mr.BrickAdventures.scripts.State;
 /// </summary>
 public class SessionState
 {
-    /// <summary>
-    /// Current level index being played.
-    /// </summary>
-    public int CurrentLevel { get; set; }
-
     /// <summary>
     /// Coins collected during this session (not yet saved).
     /// </summary>
@@ -29,7 +24,6 @@ public class SessionState
     /// </summary>
     public static SessionState CreateDefault() => new()
     {
-        CurrentLevel = 0,
         CoinsCollected = 0,
         SkillsUnlocked = new List<SkillData>()
     };
@@ -44,11 +38,10 @@ public class SessionState
     }
 
     /// <summary>
-    /// Resets completely including level.
+    /// Resets all session state.
     /// </summary>
     public void ResetAll()
     {
-        CurrentLevel = 0;
         CoinsCollected = 0;
         SkillsUnlocked.Clear();
     }