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>

SportsTimeTests/Domain/CustomItineraryItemTests.swift

@@ -0,0 +1,57 @@
+//
+//  CustomItineraryItemTests.swift
+//  SportsTimeTests
+//
+
+import Testing
+@testable import SportsTime
+import Foundation
+
+struct CustomItineraryItemTests {
+
+    @Test("Item initializes with default values")
+    func item_InitializesWithDefaults() {
+        let tripId = UUID()
+        let item = CustomItineraryItem(
+            tripId: tripId,
+            category: .restaurant,
+            title: "Joe's BBQ",
+            anchorDay: 1
+        )
+
+        #expect(item.tripId == tripId)
+        #expect(item.category == .restaurant)
+        #expect(item.title == "Joe's BBQ")
+        #expect(item.anchorType == .startOfDay)
+        #expect(item.anchorId == nil)
+        #expect(item.anchorDay == 1)
+    }
+
+    @Test("Item category has correct icons")
+    func category_HasCorrectIcons() {
+        #expect(CustomItineraryItem.ItemCategory.restaurant.icon == "🍽️")
+        #expect(CustomItineraryItem.ItemCategory.hotel.icon == "🏨")
+        #expect(CustomItineraryItem.ItemCategory.activity.icon == "🎯")
+        #expect(CustomItineraryItem.ItemCategory.note.icon == "📝")
+    }
+
+    @Test("Item is Codable")
+    func item_IsCodable() throws {
+        let item = CustomItineraryItem(
+            tripId: UUID(),
+            category: .hotel,
+            title: "Hilton Downtown",
+            anchorType: .afterGame,
+            anchorId: "game_123",
+            anchorDay: 2
+        )
+
+        let encoded = try JSONEncoder().encode(item)
+        let decoded = try JSONDecoder().decode(CustomItineraryItem.self, from: encoded)
+
+        #expect(decoded.id == item.id)
+        #expect(decoded.title == item.title)
+        #expect(decoded.anchorType == .afterGame)
+        #expect(decoded.anchorId == "game_123")
+    }
+}