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/Core/Models/Domain/CustomItineraryItem.swift

@@ -0,0 +1,83 @@
+//
+//  CustomItineraryItem.swift
+//  SportsTime
+//
+
+import Foundation
+
+struct CustomItineraryItem: Identifiable, Codable, Hashable {
+    let id: UUID
+    let tripId: UUID
+    var category: ItemCategory
+    var title: String
+    var anchorType: AnchorType
+    var anchorId: String?
+    var anchorDay: Int
+    var sortOrder: Int  // For ordering within same anchor position
+    let createdAt: Date
+    var modifiedAt: Date
+
+    init(
+        id: UUID = UUID(),
+        tripId: UUID,
+        category: ItemCategory,
+        title: String,
+        anchorType: AnchorType = .startOfDay,
+        anchorId: String? = nil,
+        anchorDay: Int,
+        sortOrder: Int = 0,
+        createdAt: Date = Date(),
+        modifiedAt: Date = Date()
+    ) {
+        self.id = id
+        self.tripId = tripId
+        self.category = category
+        self.title = title
+        self.anchorType = anchorType
+        self.anchorId = anchorId
+        self.anchorDay = anchorDay
+        self.sortOrder = sortOrder
+        self.createdAt = createdAt
+        self.modifiedAt = modifiedAt
+    }
+
+    enum ItemCategory: String, Codable, CaseIterable {
+        case restaurant
+        case hotel
+        case activity
+        case note
+
+        var icon: String {
+            switch self {
+            case .restaurant: return "🍽️"
+            case .hotel: return "🏨"
+            case .activity: return "🎯"
+            case .note: return "📝"
+            }
+        }
+
+        var label: String {
+            switch self {
+            case .restaurant: return "Restaurant"
+            case .hotel: return "Hotel"
+            case .activity: return "Activity"
+            case .note: return "Note"
+            }
+        }
+
+        var systemImage: String {
+            switch self {
+            case .restaurant: return "fork.knife"
+            case .hotel: return "bed.double.fill"
+            case .activity: return "figure.run"
+            case .note: return "note.text"
+            }
+        }
+    }
+
+    enum AnchorType: String, Codable {
+        case startOfDay
+        case afterGame
+        case afterTravel
+    }
+}