修了很多bug和增加功能，优化不少问题

Assets/songsDatabase/SongDataController/SongButton.cs

@@ -19,6 +19,10 @@ public class SongButton : MonoBehaviour
     public Text songIDText;
     public Image buttonImage;
     public Image scoreLevelImage;
+    [Header("Difficulty Level Images")]
+    public Image lvl_img_01;
+    public Image lvl_img_02;
+    public Image lvl_img_03;
     [Header("Inspector")]
     public Image profileImage;
     public int song_songSerialID;
@@ -123,6 +127,9 @@ public class SongButton : MonoBehaviour
 
             if (difficultyIDText != null) difficultyIDText.text = diffDisplay;
 
+            // Set rank images for the first three difficulties
+            SetDifficultyRankImages(sd);
+
             if (buttonImage != null) buttonImage.sprite = sd.backgroudPIC;
 
             if (profileImage != null)
@@ -153,6 +160,37 @@ public class SongButton : MonoBehaviour
         }
     }
 
+    private void SetDifficultyRankImages(SongData sd)
+    {
+        if (rankConfig == null) return;
+
+        Image[] rankImages = { lvl_img_01, lvl_img_02, lvl_img_03 };
+        
+        for (int i = 0; i < rankImages.Length; i++)
+        {
+            if (rankImages[i] == null) continue;
+
+            if (sd.chartFiles != null && i < sd.chartFiles.Count)
+            {
+                var entry = sd.chartFiles[i];
+                if (entry != null)
+                {
+                    int score = entry.totalPersonalRecordForThisDifficulty;
+                    rankImages[i].sprite = rankConfig.GetRankSprite(score);
+                    rankImages[i].enabled = rankImages[i].sprite != null;
+                }
+                else
+                {
+                    rankImages[i].enabled = false;
+                }
+            }
+            else
+            {
+                rankImages[i].enabled = false;
+            }
+        }
+    }
+
     public void OnSongButtonClick()
     {
         Debug.Log("Song button clicked, song_songSerialID: " + song_songSerialID);