feat: implement background payment sync worker and admin trigger UI

app/admin/transactions/page.tsx

@@ -11,6 +11,7 @@ import { format } from 'date-fns';
 import { tr } from 'date-fns/locale';
 import TransactionSearch from '@/components/admin/TransactionSearch';
 import TransactionStatusFilter from '@/components/admin/TransactionStatusFilter';
+import SyncPaymentsButton from '@/components/admin/SyncPaymentsButton';
 
 async function getTransactions(filters: { merchant_id?: string; q?: string; status?: string }) {
     let sql = `
@@ -71,6 +72,8 @@ export default async function TransactionsPage(props: {
                 <div className="flex items-center gap-4 flex-1">
                     <TransactionSearch />
                     <TransactionStatusFilter />
+                    <div className="h-8 w-px bg-gray-100 mx-2"></div>
+                    <SyncPaymentsButton />
                 </div>
 
                 <button className="flex items-center justify-center gap-2 px-6 py-3 bg-gray-900 text-white rounded-2xl text-sm font-bold hover:bg-gray-800 transition shadow-lg shadow-gray-200">