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/Polls/Views/PollDetailView.swift

@@ -126,7 +126,7 @@ struct PollDetailView: View {
         }
         .sheet(item: $selectedTrip) { trip in
             NavigationStack {
-                TripDetailView(trip: trip)
+                TripDetailView(trip: trip, allowCustomItems: true)
                     .navigationBarTitleDisplayMode(.inline)
                     .toolbar {
                         ToolbarItem(placement: .cancellationAction) {