feat(itinerary): add custom itinerary items with drag-to-reorder

- Add CustomItineraryItem domain model with sortOrder for ordering
- Add CKCustomItineraryItem CloudKit wrapper for persistence
- Create CustomItemService for CRUD operations
- Create CustomItemSubscriptionService for real-time sync
- Add AppDelegate for push notification handling
- Add AddItemSheet for creating/editing items
- Add CustomItemRow with drag handle
- Update TripDetailView with continuous vertical timeline
- Enable drag-to-reorder using .draggable/.dropDestination
- Add inline "Add" buttons after games and travel segments

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

SportsTime/Features/Home/Views/HomeView.swift

@@ -315,7 +315,7 @@ struct SavedTripCard: View {
 
     var body: some View {
         NavigationLink {
-            TripDetailView(trip: trip)
+            TripDetailView(trip: trip, games: savedTrip.games, allowCustomItems: true)
         } label: {
             HStack(spacing: Theme.Spacing.md) {
                 // Route preview icon
@@ -555,7 +555,7 @@ struct SavedTripsListView: View {
                 ForEach(Array(sortedTrips.enumerated()), id: \.element.id) { index, savedTrip in
                     if let trip = savedTrip.trip {
                         NavigationLink {
-                            TripDetailView(trip: trip)
+                            TripDetailView(trip: trip, games: savedTrip.games, allowCustomItems: true)
                         } label: {
                             SavedTripListRow(trip: trip)
                         }