ScheduleFlightBody "Купить" button: wire onBuy → Aeroflot booking URL

DayGroupedFlightList gains an optional `onBuy` prop that forwards to
ScheduleFlightBody. ScheduleSearchPage implements handleBuy — matches
BoardDetailsHeader.BuyTicketButton: opens
`aeroflot.ru/sb/app/{lang}-{lang}#/search?routes={dep}.{yyyyMMdd}.{arr}`
in a new tab, using the first leg's airportCode + scheduled-departure
UTC for direct and multi-leg flights.

Previously the Buy button rendered but its click was `onBuy?.()` with
no handler wired, so nothing happened. The button text + wiring now
mirror Angular's `buy-ticket-button.component`.

src/features/schedule/components/DayGroupedFlightList.tsx

@@ -32,6 +32,8 @@ export interface DayGroupedFlightListProps {
   flights: ISimpleFlight[];
   loading?: boolean;
   onFlightClick?: (flight: ISimpleFlight) => void;
+  /** Click handler for the `Купить` button inside each expanded flight body. */
+  onBuy?: (flight: ISimpleFlight) => void;
   initialCurrentFlightId?: string | null;
 }
 
@@ -125,6 +127,7 @@ export const DayGroupedFlightList: FC<DayGroupedFlightListProps> = ({
   flights,
   loading,
   onFlightClick,
+  onBuy,
   initialCurrentFlightId,
 }) => {
   const { language } = useLocale();
@@ -236,9 +239,10 @@ export const DayGroupedFlightList: FC<DayGroupedFlightListProps> = ({
       <ScheduleFlightBody
         flight={f}
         {...(onFlightClick ? { onStatus: () => onFlightClick(f) } : {})}
+        {...(onBuy ? { onBuy: () => onBuy(f) } : {})}
       />
     ),
-    [onFlightClick],
+    [onFlightClick, onBuy],
   );
 
   if (loading) return <FlightListSkeleton count={5} />;

src/features/schedule/components/ScheduleSearchPage.tsx

@@ -142,6 +142,30 @@ export const ScheduleSearchPage: FC<ScheduleSearchPageProps> = ({ params }) => {
     [locale, navigate],
   );
 
+  // `Купить` button — opens Aeroflot's booking flow in a new tab, same
+  // URL shape as BoardDetailsHeader's BuyTicketButton:
+  //   https://www.aeroflot.ru/sb/app/{lang}-{lang}#/search?…&routes={dep}.{yyyyMMdd}.{arr}
+  const handleBuy = useCallback(
+    (flight: ISimpleFlight) => {
+      const legs = flight.routeType === "Direct" ? [flight.leg] : flight.legs;
+      const firstLeg = legs[0];
+      const lastLeg = legs[legs.length - 1];
+      if (!firstLeg || !lastLeg) return;
+      const dep = firstLeg.departure.scheduled.airportCode;
+      const arr = lastLeg.arrival.scheduled.airportCode;
+      const depUtc = firstLeg.departure.times.scheduledDeparture.utc;
+      const depDate = new Date(depUtc);
+      const yyyy = depDate.getFullYear().toString();
+      const mm = (depDate.getMonth() + 1).toString().padStart(2, "0");
+      const dd = depDate.getDate().toString().padStart(2, "0");
+      const url = `https://www.aeroflot.ru/sb/app/${language}-${language}#/search?adults=1&cabin=economy&children=0&infants=0&routes=${dep}.${yyyy}${mm}${dd}.${arr}&autosearch=Y`;
+      if (typeof window !== "undefined") {
+        window.open(url, "_blank", "noopener,noreferrer");
+      }
+    },
+    [language],
+  );
+
   // Round-trip schedules render only one direction at a time, with a
   // `Туда / Обратно` switcher in the sticky header — matches Angular's
   // `schedule-direction-switch` (one-of-two button group). Default to
@@ -394,6 +418,7 @@ export const ScheduleSearchPage: FC<ScheduleSearchPageProps> = ({ params }) => {
                 flights={outboundSimple}
                 loading={outboundLoading}
                 onFlightClick={handleFlightClick}
+                onBuy={handleBuy}
               />
             </div>
           ) : (
@@ -402,6 +427,7 @@ export const ScheduleSearchPage: FC<ScheduleSearchPageProps> = ({ params }) => {
                 flights={inboundSimple}
                 loading={inboundLoading}
                 onFlightClick={handleFlightClick}
+                onBuy={handleBuy}
               />
             </div>
           )}