refactor(ProcessPostUseCase, useCursorPagination, useDifferentialPosts): enhance post merging and loading states

- Introduced new methods for merging posts and comments efficiently, improving performance during data updates.
- Updated loading state management in hooks to include initial loading and loading more states for better user feedback.
- Refactored HomeScreen and PostDetailScreen to utilize the new loading states and merging logic, enhancing user experience during data fetching.
- Improved pagination handling in useCursorPagination and useDifferentialPosts to ensure consistent data management across components.

src/hooks/useDifferentialPosts.ts

@@ -70,6 +70,10 @@ export interface UseDifferentialPostsResult<T extends PostIdentifier> {
   posts: T[];
   /** 是否正在加载 */
   loading: boolean;
+  /** 是否首屏加载 */
+  isInitialLoading: boolean;
+  /** 是否正在加载更多 */
+  isLoadingMore: boolean;
   /** 是否正在刷新 */
   refreshing: boolean;
   /** 错误信息 */
@@ -514,6 +518,8 @@ export function useDifferentialPosts<T extends PostIdentifier = Post>(
   return {
     posts,
     loading,
+    isInitialLoading: loading && posts.length === 0 && !refreshing,
+    isLoadingMore: loading && posts.length > 0 && !refreshing,
     refreshing,
     error,
     hasMore,