Fix iCloud sync: chart and next check-in date stale on secondary device (build 32)

- completedMonthKeys: remove UserDefaults-based MonthlyCheckInStore check (not synced via iCloud)
- MonthlyCheckInCard.effectiveLastCheckInDate: use max() instead of ?? to prefer newer synced snapshot date
- MonthlyCheckInView.lastCompletionDate: use max() of local + latest CoreData snapshot via @FetchRequest
- FirebaseService.logPaywallShown: fix parameter key to paywall_trigger (matches GA4 custom dimension)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

PortfolioJournal/Views/Dashboard/DashboardView.swift

@@ -599,7 +599,10 @@ struct MonthlyCheckInCard: View {
     @State private var cachedCompletionDate: Date?
 
     private var effectiveLastCheckInDate: Date? {
-        cachedCompletionDate ?? lastUpdatedDate
+        // Use whichever is more recent: local completion record or latest snapshot date from CoreData.
+        // cachedCompletionDate lives in UserDefaults (device-local, not iCloud-synced), so on a
+        // secondary device after iCloud sync the snapshot date may be newer than the local record.
+        [cachedCompletionDate, lastUpdatedDate].compactMap { $0 }.max()
     }
 
     private var checkInProgress: Double {