add chartinfo implementation

src/Data/Database.cs

@@ -80,7 +80,7 @@ public static class Database
 
                     // TODO: check audio existence; add warning but don't skip
 
-                    song.Levels[(int)diff] = lvl;
+                    song.Levels[(int)diff] = (lvl, data[Consts.DIFF_DESIGNER_KEY[diff]].ToString()!);
                 }
 
                 Dispatcher.UIThread.Post(() => Songs.Add(song));

src/Data/Song/Consts.cs

@@ -58,4 +58,12 @@ public static class Consts
         {Difficulty.Inferno, "ClearNormaRateInferno"},
     };
     public static readonly IReadOnlyDictionary<Difficulty, string> DIFF_CLEAR_KEY = _DIFF_CLEAR_KEY;
+
+    public static readonly IReadOnlyDictionary<Difficulty, string> DIFF_DESIGNER_KEY = new Dictionary<Difficulty, string>()
+    {
+        {Difficulty.Normal, "NotesDesignerNormal"},
+        {Difficulty.Hard, "NotesDesignerHard"},
+        {Difficulty.Expert, "NotesDesignerExpert"},
+        {Difficulty.Inferno, "NotesDesignerInferno"},
+    };
 }

src/Data/Song/Song.cs

@@ -22,7 +22,7 @@ public class Song
     public required float PreviewTime { get; set; }
     public required float PreviewLen { get; set; }
     public string SourceName => Consts.NUM_SOURCE[Source];
-    public float?[] Levels { get; set; } = { null, null, null, null };
+    public (float, string)?[] Levels { get; set; } = { null, null, null, null };
     
 
     // TODO: For SaturnData.Entry instances, use this Guid format: