[#73968] Move card metrics to Backlogs

Remove the story-points display from the shared work package card and
expose a generic metric slot instead. Backlogs now opts into that slot
with a small story-points component when rendering sprint, bucket, and
inbox cards.

https://community.openproject.org/wp/73968

lookbook/previews/open_project/common/work_package_card_box_component_preview.rb

@@ -41,7 +41,9 @@ module OpenProject
 
         work_packages = sprint.work_packages_for(project).limit(3)
         render OpenProject::Common::WorkPackageCardBoxComponent.new(
-          work_packages:, project:, container: sprint
+          work_packages:,
+          project:,
+          container: sprint
         ) do |box|
           box.with_header(title: sprint.name, count: work_packages.size) do |header|
             points = work_packages.sum { |w| w.story_points || 0 }

lookbook/previews/open_project/common/work_package_card_component_preview.rb

@@ -41,6 +41,19 @@ module OpenProject
         )
       end
 
+      def with_metric
+        work_package = WorkPackage.first
+        return preview_message("No work packages in the database.") unless work_package
+
+        render OpenProject::Common::WorkPackageCardComponent.new(
+          work_package:
+        ) do |card|
+          card.with_metric do
+            render Backlogs::StoryPointsComponent.new(work_package:)
+          end
+        end
+      end
+
       private
 
       def preview_message(text)