fix: tolerate num-typed JSON color entries in SeasonTheme

lib/game/models/season.dart

@@ -17,12 +17,12 @@ class SeasonTheme {
         tileSet: (json['tileSet'] as String?) ?? 'spring',
         background: (json['background'] as String?) ?? '',
         backgroundGradient: json['backgroundGradient'] != null
-            ? [for (final c in json['backgroundGradient'] as List) c as int]
+            ? [for (final c in json['backgroundGradient'] as List) (c as num).toInt()]
             : defaultGradient,
         accentColor: (json['accentColor'] as int?) ?? 0xFFFF7EB3,
         particleType: (json['particleType'] as String?) ?? 'petals',
         tilePalette: json['tilePalette'] != null
-            ? [for (final c in json['tilePalette'] as List) c as int]
+            ? [for (final c in json['tilePalette'] as List) (c as num).toInt()]
             : null,
         boardTint: json['boardTint'] as int?,
       );
@@ -42,7 +42,7 @@ class SeasonTheme {
   /// petals | snow | leaves | none
   final String particleType;
 
-  /// Optional 8-color tile override; null = built-in candy palette.
+  /// Optional tile color override; null = built-in candy palette.
   final List<int>? tilePalette;
 
   /// Optional board background override.