refactor(post): consolidate post sync to PostSyncService and remove ProcessPostUseCase

- Replace ProcessPostUseCase with new PostSyncService in src/services/post/
- Add postListStore for state management in src/stores/post/
- Remove deprecated ProcessPostUseCase and ProcessMessageUseCase files
- Delete architecture documentation files (ARCHITECTURE_REFACTOR_PLAN.md, architecture-comparison-report.md)
- Update all consumers (HomeScreen, PostDetailScreen, SearchScreen, useUserProfile, useDifferentialPosts)
- Simplify postService to only contain API layer methods
- Remove unused type exports from message stores

BREAKING CHANGE: ProcessPostUseCase and ProcessMessageUseCase have been removed.
Use postSyncService for post operations instead.

src/screens/profile/useUserProfile.ts

@@ -12,6 +12,7 @@ import { Post, User } from '../../types';
 import { useUserStore } from '../../stores';
 import { useCurrentUser } from '../../stores/authStore';
 import { postService, authService, messageService } from '../../services';
+import { postSyncService } from '../../services/post/PostSyncService';
 import { userManager } from '../../stores/userManager';
 import * as hrefs from '../../navigation/hrefs';
 import { PostCardAction } from '../../components/business/PostCard';
@@ -310,16 +311,23 @@ export const useUserProfile = (options: UseUserProfileOptions): UseUserProfileRe
           handleUserPress(post.author.id);
         }
         break;
-      case 'like':
+case 'like':
       case 'unlike':
-        post.is_liked ? postService.unlikePost(post.id) : postService.likePost(post.id);
+        post.is_liked ? postSyncService.unlikePost(post.id) : postSyncService.likePost(post.id);
         break;
       case 'comment':
         handlePostPress(post.id, true);
         break;
       case 'bookmark':
       case 'unbookmark':
-        post.is_favorited ? postService.unfavoritePost(post.id) : postService.favoritePost(post.id);
+        post.is_favorited ? postSyncService.unfavoritePost(post.id) : postSyncService.favoritePost(post.id);
+        break;
+      case 'comment':
+        handlePostPress(post.id, true);
+        break;
+      case 'bookmark':
+      case 'unbookmark':
+        post.is_favorited ? postSyncService.unfavoritePost(post.id) : postSyncService.favoritePost(post.id);
         break;
       case 'share':
         break;