fix(private-room): preserve payment return route

src/lib/payment/payment_search_params.ts

@@ -1,4 +1,5 @@
 import type { PayChannel } from "@/data/dto/payment";
+import type { AppSubscriptionReturnTo } from "@/router/navigation-types";
 
 export type PaymentSearchParamValue = string | string[] | undefined;
 export type PaymentSearchParams = Record<string, PaymentSearchParamValue>;
@@ -21,6 +22,14 @@ export function parsePaymentPayChannel(
   return channel === "ezpay" || channel === "stripe" ? channel : null;
 }
 
+export function parseSubscriptionReturnTo(
+  value: PaymentSearchParamValue,
+): AppSubscriptionReturnTo {
+  const returnTo = getFirstPaymentSearchParam(value);
+  if (returnTo === "chat" || returnTo === "private-room") return returnTo;
+  return null;
+}
+
 export function parsePaymentReturnSearchParams(
   searchParams: PaymentSearchParams,
 ): PaymentReturnSearchParams {