refactor: extract shared payment status sets to utility module

- Move PAID_STATUSES/FAILED_STATUSES from Balance.tsx and TopUpResult.tsx
  to src/utils/paymentStatus.ts
- Eliminates code duplication between the two pages

src/utils/paymentStatus.ts

@@ -0,0 +1,31 @@
+export const PAID_STATUSES = new Set([
+  'succeeded',
+  'success',
+  'paid',
+  'paid_over',
+  'overpaid',
+  'completed',
+  'confirmed',
+  'closed',
+]);
+
+export const FAILED_STATUSES = new Set([
+  'fail',
+  'failed',
+  'error',
+  'canceled',
+  'cancelled',
+  'declined',
+  'expired',
+  'cancel',
+  'system_fail',
+  'refund_paid',
+]);
+
+export function isPaidStatus(status: string): boolean {
+  return PAID_STATUSES.has(status.toLowerCase());
+}
+
+export function isFailedStatus(status: string): boolean {
+  return FAILED_STATUSES.has(status.toLowerCase());
+}