feat(finance): show sum of ordergroup balances

app/controllers/finance/ordergroups_controller.rb

@@ -11,7 +11,10 @@ class Finance::OrdergroupsController < Finance::BaseController
     @ordergroups = Ordergroup.undeleted.order(sort)
     @ordergroups = @ordergroups.include_transaction_class_sum
     @ordergroups = @ordergroups.where('groups.name LIKE ?', "%#{params[:query]}%") unless params[:query].nil?
-
     @ordergroups = @ordergroups.page(params[:page]).per(@per_page)
+
+    @total_balances = FinancialTransactionClass.sorted.each_with_object({}) do |c, tmp|
+      tmp[c.id] = c.financial_transactions.reduce(0) { | sum, t | sum + t.amount }
+    end
   end
 end