feat: add pagination to admin post list handler and service

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

services/posts/list.go

@@ -12,29 +12,36 @@ type PostWithCategories struct {
 	Categories []*models.Category
 }
 
-func (s *Service) ListPosts(ctx context.Context, showDeleted bool) ([]*PostWithCategories, error) {
+type ListPostsResult struct {
+	Posts      []*PostWithCategories
+	TotalCount int64
+}
+
+func (s *Service) ListPosts(ctx context.Context, showDeleted bool, paging db.PagingParams) (ListPostsResult, error) {
 	site, ok := models.GetSite(ctx)
 	if !ok {
-		return nil, models.SiteRequiredError
+		return ListPostsResult{}, models.SiteRequiredError
 	}
 
-	posts, err := s.db.SelectPostsOfSite(ctx, site.ID, showDeleted, db.PagingParams{
-		Offset: 0,
-		Limit:  25,
-	})
+	posts, err := s.db.SelectPostsOfSite(ctx, site.ID, showDeleted, paging)
 	if err != nil {
-		return nil, err
+		return ListPostsResult{}, err
+	}
+
+	count, err := s.db.CountPostsOfSite(ctx, site.ID, showDeleted)
+	if err != nil {
+		return ListPostsResult{}, err
 	}
 
 	result := make([]*PostWithCategories, len(posts))
 	for i, post := range posts {
 		cats, err := s.db.SelectCategoriesOfPost(ctx, post.ID)
 		if err != nil {
-			return nil, err
+			return ListPostsResult{}, err
 		}
 		result[i] = &PostWithCategories{Post: post, Categories: cats}
 	}
-	return result, nil
+	return ListPostsResult{Posts: result, TotalCount: count}, nil
 }
 
 func (s *Service) GetPost(ctx context.Context, pid int64) (*models.Post, error) {