fix: add missing StyledTextStyleMixin export and clean up imports

- Export StyledTextStyleMixin from style.dart for consistency with other mixins
- Remove redundant direct import in callout.dart (now provided by style.dart)
- Remove misleading comment about non-existent RemixTokens class

Author: claude

packages/remix/lib/src/components/callout/callout.dart

@@ -4,7 +4,6 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:mix/mix.dart';
 
-import '../../style/mixins/styled_text_style_mixin.dart';
 import '../../style/style.dart';
 import '../../utilities/remix_style.dart';
 import '../../fortal/fortal.dart';

packages/remix/lib/src/style/style.dart

@@ -3,3 +3,4 @@
 export 'mixins/icon_style_mixin.dart';
 export 'mixins/label_style_mixin.dart';
 export 'mixins/spinner_style_mixin.dart';
+export 'mixins/styled_text_style_mixin.dart';

packages/remix/lib/src/theme/remix_theme.dart

@@ -33,7 +33,6 @@ Widget createRemixScope({
     );
 
     // Use createFortalScope which provides all the token values
-    // RemixTokens now just references FortalTokens, so this provides everything
     return createFortalScope(
       accent: accent,
       gray: gray,