feat: add multi-day transport reservations with dedicated modal and route segmentation

Introduces a TransportModal for creating/editing flight, train, car, and cruise
reservations that span multiple days. Transport entries now break the map route
into disconnected segments so the polyline reflects actual travel legs.

- Add TransportModal with airport/location pickers, multi-day date range, and all transport types
- Extend DB schema with end_day_id on reservations (migration 110) and backfill from existing dates
- Refactor useRouteCalculation to emit [][][number,number] segments split at transport boundaries
- Update MapView, DayPlanSidebar, ReservationsPanel, TripPlannerPage to wire up transport flow
- Add transport i18n keys across all 15 languages

client/tests/integration/hooks/useRouteCalculation.test.ts

@@ -20,7 +20,8 @@ const { calculateSegments } = await import('../../../src/components/Map/RouteCal
 function buildMockStore(assignments: Record<string, ReturnType<typeof buildAssignment>[]> = {}): Partial<TripStoreState> {
   // Also populate the real Zustand store so updateRouteForDay (which reads from
   // useTripStore.getState()) sees the same assignments as the hook's tripStore param.
-  useTripStore.setState({ assignments } as any);
+  // Reset reservations and days to empty so transport-split logic doesn't interfere.
+  useTripStore.setState({ assignments, reservations: [], days: [] } as any);
   return { assignments } as Partial<TripStoreState>;
 }
 
@@ -77,9 +78,9 @@ describe('useRouteCalculation', () => {
     );
 
     await act(async () => {});
+    // route is an array of segments; no transport → single segment with all places
     expect(result.current.route).toEqual([
-      [p1.lat, p1.lng],
-      [p2.lat, p2.lng],
+      [[p1.lat, p1.lng], [p2.lat, p2.lng]],
     ]);
   });
 
@@ -139,8 +140,7 @@ describe('useRouteCalculation', () => {
 
     // After sort: a2 (order_index=0) first, then a1 (order_index=1)
     expect(result.current.route).toEqual([
-      [p2.lat, p2.lng],
-      [p1.lat, p1.lng],
+      [[p2.lat, p2.lng], [p1.lat, p1.lng]],
     ]);
   });
 
@@ -289,8 +289,7 @@ describe('useRouteCalculation', () => {
     await act(async () => {});
 
     expect(result.current.route).toEqual([
-      [p1.lat, p1.lng],
-      [p2.lat, p2.lng],
+      [[p1.lat, p1.lng], [p2.lat, p2.lng]],
     ]);
 
     // Now add a third place — update both the local store object and the Zustand store
@@ -305,9 +304,7 @@ describe('useRouteCalculation', () => {
     await act(async () => {});
 
     expect(result.current.route).toEqual([
-      [p1.lat, p1.lng],
-      [p2.lat, p2.lng],
-      [p3.lat, p3.lng],
+      [[p1.lat, p1.lng], [p2.lat, p2.lng], [p3.lat, p3.lng]],
     ]);
   });
 });