Add MeleeEffect and related services for combat interactions

GameCore/State/IGameStateService.cs

@@ -0,0 +1,13 @@
+namespace GameCore.State;
+
+public interface IGameStateService
+{
+    GameStatus CurrentStatus { get; }
+    string CurrentLevelId { get; }
+    IReadOnlyCollection<string> UnlockedLevelIds { get; }
+
+    void SetStatus(GameStatus newStatus);
+    void StartGame(string startingLevelId);
+    void UnlockLevel(string levelId);
+    void ResetProgress();
+}