refactor(repetition): add row_id to champs

app/jobs/migrations/backfill_row_id_job.rb

@@ -0,0 +1,7 @@
+class Migrations::BackfillRowIdJob < ApplicationJob
+  def perform(batch)
+    batch.each do |(row_id, champ_ids)|
+      Champ.where(id: champ_ids).update_all(row_id:)
+    end
+  end
+end