routes: keep paging when client-side region filtering starves the table

A multi-IATA region filters globally-paged rows client-side, and scroll
was the only trigger for the next page — an empty or too-short filtered
list could never fire it, so routes deeper in the cursor stream were
unreachable ('No routes' with routes that exist). Pull pages until the
region has a screenful or the cap calls it sparse.

src/features/routes/RouteTable.tsx

@@ -169,7 +169,7 @@ export function RouteTable() {
 
   // Page the route set on demand (50 at a time, cursor = last route's lastSeen ms) — the DataTable
   // pulls the next page via loadMore() as you scroll, instead of eagerly loading the whole set.
-  const { items: listRoutes, loadedCount, isPaging, isError, isLoading: listLoading, loadMore } =
+  const { items: listRoutes, loadedCount, isPaging, isError, isLoading: listLoading, loadMore, hasMore } =
     useInfinitePages<KnownRoute>({
       queryKey: ["routes", serverIata ?? ""],
       queryFn: (cursor) => getKnownRoutesPage({ iata: serverIata, cursor }),
@@ -223,6 +223,16 @@ export function RouteTable() {
     [rows, selectedKey],
   );
 
+  // A multi-IATA region filters globally-paged rows client-side, so the filtered list can be too
+  // short to ever trigger scroll paging — or empty, with the region's routes deeper in the cursor
+  // stream. Keep pulling pages until there's a screenful or the cap says the region is just sparse.
+  useEffect(() => {
+    if (search || serverIata || !iatas?.length) return;
+    if (!hasMore || isPaging) return;
+    if ((rows?.length ?? 0) >= 50 || loadedCount >= 1000) return;
+    loadMore();
+  }, [search, serverIata, iatas, hasMore, isPaging, rows, loadedCount, loadMore]);
+
   const canSearch = !!(from.trim() && to.trim() && searchIatas.length >= 1);
   // clear any selection when the visible list changes out from under it (search submit/clear)
   const submitSearch = useCallback(() => {