feat: NanumGothic font + SongSelect UI fixes

- Add NanumGothic.ttf and NanumGothic SDF.asset for Korean text support
- SongSelectManager: cardFont SerializeField for card title/artist rendering
- SongDetailPanel: difficulty selected color changed from blue to green

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Assets/Script/SongDetailPanel.cs

@@ -33,7 +33,7 @@ public class SongDetailPanel : MonoBehaviour
     [Header("씬 이름")]
     [SerializeField] private string gameSceneName = "Game";
 
-    private static readonly Color SelectedColor   = new Color(0.4f, 0.8f, 1f);
+    private static readonly Color SelectedColor   = new Color(0.2f, 0.78f, 0.4f);
     private static readonly Color DeselectedColor = Color.white;
 
     private SongInfo          currentSong;

Assets/Script/SongSelectManager.cs

@@ -14,6 +14,7 @@ public class SongSelectManager : MonoBehaviour
     [SerializeField] private GameObject      loadingOverlay;
     [SerializeField] private GameObject      errorOverlay;
     [SerializeField] private TMP_Text        errorText;
+    [SerializeField] private TMP_FontAsset   cardFont;
 
     private static readonly Color TabActive   = Color.white;
     private static readonly Color TabInactive = new Color(0.6f, 0.6f, 0.6f);
@@ -129,6 +130,7 @@ public class SongSelectManager : MonoBehaviour
         tr.offsetMin = new Vector2(5f, 0f);
         tr.offsetMax = new Vector2(downloaded ? -18f : -3f, -1f);
         var tTmp = titleGO.AddComponent<TextMeshProUGUI>();
+        if (cardFont != null) tTmp.font = cardFont;
         tTmp.text         = song.title;
         tTmp.fontSize     = 5f;
         tTmp.color        = Color.white;
@@ -144,6 +146,7 @@ public class SongSelectManager : MonoBehaviour
         ar.offsetMin = new Vector2(5f, 1f);
         ar.offsetMax = new Vector2(-3f, 0f);
         var aTmp = artistGO.AddComponent<TextMeshProUGUI>();
+        if (cardFont != null) aTmp.font = cardFont;
         aTmp.text      = song.artist;
         aTmp.fontSize  = 4f;
         aTmp.color     = new Color(1f, 1f, 1f, 0.6f);

Assets/TextMesh Pro/Fonts/NanumGothic SDF.asset.meta

@@ -0,0 +1,8 @@
+fileFormatVersion: 2
+guid: f6c6fe0f3c5912a43a8a6707e336d2ea
+NativeFormatImporter:
+  externalObjects: {}
+  mainObjectFileID: 11400000
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Assets/TextMesh Pro/Fonts/NanumGothic.ttf.meta

@@ -0,0 +1,21 @@
+fileFormatVersion: 2
+guid: d2abafb75e12afe48bb523e2ac30b43b
+TrueTypeFontImporter:
+  externalObjects: {}
+  serializedVersion: 4
+  fontSize: 16
+  forceTextureCase: -2
+  characterSpacing: 0
+  characterPadding: 1
+  includeFontData: 1
+  fontNames:
+  - NanumGothic
+  fallbackFontReferences: []
+  customCharacters: 
+  fontRenderingMode: 0
+  ascentCalculationMode: 1
+  useLegacyBoundsCalculation: 0
+  shouldRoundAdvanceValue: 1
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: