Fix schedule flight details 404: use Modern.js $.tsx splat route convention

The [...flights]/page.tsx catch-all generated an incorrect route pattern
(schedule/:/flights) instead of a React Router splat (schedule/*).

Modern.js convention for catch-all routes is $.tsx at the directory level,
not [...param]/page.tsx. Moved to $.tsx and updated param access to use
the "*" splat key.

Fixes: /ru/schedule/SU0012-20220527 and multi-leg URLs now resolve.

src/routes/[lang]/schedule/$.tsx

@@ -49,13 +49,12 @@ function parseFlightSegments(segments: string[]): IScheduleFlightId[] {
 }
 
 export default function ScheduleDetailsRoute(): JSX.Element {
-  const routeParams = useParams<{ flights: string; lang: string }>();
+  const routeParams = useParams<{ "*": string; lang: string }>();
   const locale = routeParams.lang ?? "ru";
   const canonicalOrigin = getEnv().PROD_ORIGIN;
 
-  // Modern.js catch-all provides the remaining path as a single string
-  // joined by "/". We split it back to segments.
-  const rawFlights = routeParams.flights ?? "";
+  // Modern.js $.tsx splat route provides the remaining path via "*" param.
+  const rawFlights = routeParams["*"] ?? "";
   const segments = rawFlights.split("/").filter(Boolean);
   const flights = parseFlightSegments(segments);