refactor(PostCard, PostCard.legacy): remove legacy PostCard component and update exports

- Deleted the legacy PostCard component to streamline the codebase and improve maintainability.
- Updated exports in PostCard and index files to remove references to the legacy component.
- Adjusted PostCardProps to eliminate legacy properties, ensuring only the new API is supported.
- Enhanced the PostCard component to focus on modern implementation and features.

src/components/business/index.ts

@@ -13,10 +13,7 @@ export type {
   PostCardFeaturesPreset,
   PostCardFeaturesConfig,
   PostCardProps,
-  LegacyPostCardProps,
 } from './PostCard';
-export { PostCardPresets, resolveFeatures } from './PostCard';
-export { usePostCardActions, usePostCardFeatures } from './PostCard';
 export { default as CommentItem } from './CommentItem';
 export { default as UserProfileHeader } from './UserProfileHeader';
 export { default as SystemMessageItem } from './SystemMessageItem';