feat: iCloud KV Store sync for tasks, workout data, and settings

- Add NSUbiquitousKeyValueStore entitlement to KisaniCal.entitlements
- New CloudSyncManager: mirrors UserDefaults to iCloud KV Store on every save; restores to UserDefaults on fresh install when local data is missing; observes external changes to pull updates in real-time; guards against 1 MB limit
- TaskViewModel: restore from iCloud on init, push to iCloud on every save
- WorkoutViewModel: restore programs/schedule/activePid/completedDates from iCloud on init, push all four keys on every save
- ContentView: restoreSettings() + backupSettings() on appear and foreground — syncs ~18 small settings keys (appearance, tabs, tutorial flags, calendar prefs, workout notifications)

Co-Authored-By: Kutesir <tqwyy79vzn@privaterelay.appleid.com>

KisaniCal/ContentView.swift

@@ -84,11 +84,14 @@ struct ContentView: View {
         }
         .onAppear {
             if !hasOnboarded { showOnboarding = true }
+            CloudSyncManager.shared.restoreSettings()
+            CloudSyncManager.shared.backupSettings()
             NotificationManager.shared.reschedule(workoutVM: workoutVM, taskVM: taskVM)
         }
         .onChange(of: scenePhase) { phase in
             if phase == .active {
                 taskVM.reload()
+                CloudSyncManager.shared.backupSettings()
                 NotificationManager.shared.reschedule(workoutVM: workoutVM, taskVM: taskVM)
             }
         }