feat(route building): add time constraint for departure requests

lib/main.dart

@@ -273,9 +273,11 @@ class StationList extends StatelessWidget {
 class ChooseDeparturePage extends StatefulWidget {
   final Station startStation;
   final int? journeyId;
+  final Departure? arrival;
   const ChooseDeparturePage({
     super.key,
     this.journeyId,
+    this.arrival,
     required this.startStation,
   });
 
@@ -288,7 +290,10 @@ class _ChooseDeparturePageState extends State<ChooseDeparturePage> {
   Journey? singleJourney;
 
   void loadDepartures(Station startStation) async {
-    departureList = await ApiHandler.departures(startStation.id);
+    departureList = await ApiHandler.departures(
+      startStation.id,
+      time: widget.arrival?.arrivalTime ?? DateTime.now(),
+    );
     setState(() {});
   }
 
@@ -470,6 +475,7 @@ class _ChooseArrivalPageState extends State<ChooseArrivalPage> {
         builder: (context) => ChooseDeparturePage(
           startStation: startStation,
           journeyId: journeyId,
+          arrival: arrival,
         ),
       ),
     );