feat(ProcessPostUseCase, HomeScreen, PostDetailScreen, PostService): implement share count synchronization after post sharing

- Added applyShareCountUpdate method in ProcessPostUseCase to synchronize share counts across post lists and details.
- Updated sharePost method in PostService to return the latest shares_count from the server.
- Modified share handling in HomeScreen and PostDetailScreen to utilize the new share count synchronization logic after a successful share operation.
- Enhanced error handling for share operations to improve user feedback.

src/core/usecases/ProcessPostUseCase.ts

@@ -333,6 +333,35 @@ class ProcessPostUseCase {
     });
   }
 
+  /**
+   * 分享计数上报成功后，同步各列表与详情中的分享数
+   */
+  applyShareCountUpdate(postId: string, sharesCount: number): void {
+    this.postsState.forEach((state, key) => {
+      const index = state.posts.findIndex((p) => p.id === postId);
+      if (index !== -1) {
+        const newPosts = [...state.posts];
+        const cur = newPosts[index];
+        newPosts[index] = {
+          ...cur,
+          sharesCount,
+          shares_count: sharesCount,
+        };
+        this.updatePostsState(key, { posts: newPosts });
+      }
+    });
+    const detail = this.getPostDetailState(postId);
+    if (detail.post) {
+      this.updatePostDetailState(postId, {
+        post: {
+          ...detail.post,
+          sharesCount,
+          shares_count: sharesCount,
+        },
+      });
+    }
+  }
+
   // ==================== 帖子列表操作 ====================
 
   /**