feat: SongSelect UI polish — marquee title, button states, font

- MarqueeText: scrolling title for long song names (RectMask2D clipped)
- SongDetailPanel: difficulty selected = green (img.color direct set)
- SongSelectManager: ALL/OWNED tab active state via img.color
- Card layout: DestroyImmediate + correct rebuild order to fix zero-size title bug
- NanumGothic SDF fallback configured on LiberationSans for Korean support

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

Assets/TextMesh Pro/Fonts/NanumGothic SDF.asset

@@ -257917,7 +257917,8 @@ MonoBehaviour:
     m_MarkToBaseAdjustmentRecords: []
     m_MarkToMarkAdjustmentRecords: []
   m_ShouldReimportFontFeatures: 0
-  m_FallbackFontAssetTable: []
+  m_FallbackFontAssetTable:
+  - {fileID: 11400000}
   m_FontWeightTable:
   - regularTypeface: {fileID: 0}
     italicTypeface: {fileID: 0}
@@ -258046,9 +258047,9 @@ Material:
     - _OutlineWidth: 0
     - _PerspectiveFilter: 0.875
     - _Reflectivity: 10
-    - _ScaleRatioA: 1
-    - _ScaleRatioB: 1
-    - _ScaleRatioC: 1
+    - _ScaleRatioA: 0
+    - _ScaleRatioB: 0
+    - _ScaleRatioC: 0
     - _ScaleX: 1
     - _ScaleY: 1
     - _ShaderFlags: 0