feat: implement payout system database schema and models

db/migrate/20250916215118_add_payout_fields_to_events.rb

@@ -0,0 +1,6 @@
+class AddPayoutFieldsToEvents < ActiveRecord::Migration[8.0]
+  def change
+    add_column :events, :payout_requested_at, :datetime
+    add_column :events, :payout_status, :integer
+  end
+end