feat: show n_size on parent graph

app/presenters/analyze/graph/column/grouped_bar_column_presenter.rb

@@ -64,7 +64,7 @@ module Analyze
         end
 
         def show_popover?
-          %i[student teacher].include? type
+          %i[student teacher parent].include? type
         end
 
         def popover_content(academic_year)

app/presenters/analyze/graph/column/parent/scale.rb

@@ -37,6 +37,10 @@ module Analyze
           def type
             :parent
           end
+
+          def n_size(measure:, school:, academic_year:)
+            SurveyItemResponse.where(survey_item: scale.survey_items.parent_survey_items, school:, academic_year:).select(:response_id).distinct.count
+          end
         end
       end
     end