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/CloudKit/CKModels.swift

@@ -20,6 +20,7 @@ enum CKRecordType {
     static let stadiumAlias = "StadiumAlias"
     static let tripPoll = "TripPoll"
     static let pollVote = "PollVote"
+    static let customItineraryItem = "CustomItineraryItem"
 }
 
 // MARK: - CKTeam
@@ -622,3 +623,74 @@ struct CKPollVote {
         )
     }
 }
+
+// MARK: - CKCustomItineraryItem
+
+struct CKCustomItineraryItem {
+    static let itemIdKey = "itemId"
+    static let tripIdKey = "tripId"
+    static let categoryKey = "category"
+    static let titleKey = "title"
+    static let anchorTypeKey = "anchorType"
+    static let anchorIdKey = "anchorId"
+    static let anchorDayKey = "anchorDay"
+    static let sortOrderKey = "sortOrder"
+    static let createdAtKey = "createdAt"
+    static let modifiedAtKey = "modifiedAt"
+
+    let record: CKRecord
+
+    init(record: CKRecord) {
+        self.record = record
+    }
+
+    init(item: CustomItineraryItem) {
+        let record = CKRecord(
+            recordType: CKRecordType.customItineraryItem,
+            recordID: CKRecord.ID(recordName: item.id.uuidString)
+        )
+        record[CKCustomItineraryItem.itemIdKey] = item.id.uuidString
+        record[CKCustomItineraryItem.tripIdKey] = item.tripId.uuidString
+        record[CKCustomItineraryItem.categoryKey] = item.category.rawValue
+        record[CKCustomItineraryItem.titleKey] = item.title
+        record[CKCustomItineraryItem.anchorTypeKey] = item.anchorType.rawValue
+        record[CKCustomItineraryItem.anchorIdKey] = item.anchorId
+        record[CKCustomItineraryItem.anchorDayKey] = item.anchorDay
+        record[CKCustomItineraryItem.sortOrderKey] = item.sortOrder
+        record[CKCustomItineraryItem.createdAtKey] = item.createdAt
+        record[CKCustomItineraryItem.modifiedAtKey] = item.modifiedAt
+        self.record = record
+    }
+
+    func toItem() -> CustomItineraryItem? {
+        guard let itemIdString = record[CKCustomItineraryItem.itemIdKey] as? String,
+              let itemId = UUID(uuidString: itemIdString),
+              let tripIdString = record[CKCustomItineraryItem.tripIdKey] as? String,
+              let tripId = UUID(uuidString: tripIdString),
+              let categoryString = record[CKCustomItineraryItem.categoryKey] as? String,
+              let category = CustomItineraryItem.ItemCategory(rawValue: categoryString),
+              let title = record[CKCustomItineraryItem.titleKey] as? String,
+              let anchorTypeString = record[CKCustomItineraryItem.anchorTypeKey] as? String,
+              let anchorType = CustomItineraryItem.AnchorType(rawValue: anchorTypeString),
+              let anchorDay = record[CKCustomItineraryItem.anchorDayKey] as? Int,
+              let createdAt = record[CKCustomItineraryItem.createdAtKey] as? Date,
+              let modifiedAt = record[CKCustomItineraryItem.modifiedAtKey] as? Date
+        else { return nil }
+
+        let anchorId = record[CKCustomItineraryItem.anchorIdKey] as? String
+        let sortOrder = record[CKCustomItineraryItem.sortOrderKey] as? Int ?? 0
+
+        return CustomItineraryItem(
+            id: itemId,
+            tripId: tripId,
+            category: category,
+            title: title,
+            anchorType: anchorType,
+            anchorId: anchorId,
+            anchorDay: anchorDay,
+            sortOrder: sortOrder,
+            createdAt: createdAt,
+            modifiedAt: modifiedAt
+        )
+    }
+}