feat(ios): add error handling and integration tests

Implement comprehensive error handling and integration test suite:

Error Handling (Section 8):
- Add iOS-specific error codes to DailyNotificationErrorCodes:
  - NOTIFICATION_PERMISSION_DENIED
  - PENDING_NOTIFICATION_LIMIT_EXCEEDED
  - BG_TASK_NOT_REGISTERED
  - BG_TASK_EXECUTION_FAILED
  - BACKGROUND_REFRESH_DISABLED
- Add helper methods for iOS-specific error responses
- Enhance error handling in ReactivationManager:
  - Database errors handled gracefully (non-fatal)
  - Notification center errors handled gracefully (non-fatal)
  - Scheduling errors handled gracefully (non-fatal)
  - All errors logged, app continues normally
  - Partial results returned when operations fail
- Update plugin methods to use iOS-specific error codes:
  - getNotificationPermissionStatus uses NOTIFICATION_PERMISSION_DENIED

Integration Tests (Section 9.2):
- Add DailyNotificationRecoveryIntegrationTests:
  - Full recovery flow tests (cold start, termination)
  - Error handling tests (database, notification center, scheduling)
  - App stability tests (no crashes, concurrent operations)
  - Partial recovery tests
  - Timeout handling tests
- Test coverage:
  - 10 integration tests covering recovery scenarios
  - Error handling verification
  - App stability verification
  - Concurrent operation safety

Completes sections 8.1, 8.2, and 9.2 of iOS implementation checklist.

ios/Plugin/DailyNotificationReactivationManager.swift

@@ -189,14 +189,32 @@ class DailyNotificationReactivationManager {
      */
     internal func detectScenario() async throws -> RecoveryScenario {
         // Step 1: Check if database has notifications
-        let allNotifications = storage.getAllNotifications()
+        // Handle storage errors gracefully (non-fatal)
+        let allNotifications: [NotificationContent]
+        do {
+            allNotifications = storage.getAllNotifications()
+        } catch {
+            // Non-fatal: Log error and assume empty storage
+            NSLog("\(Self.TAG): Error getting notifications from storage (non-fatal): \(error.localizedDescription)")
+            return .none
+        }
         
         if allNotifications.isEmpty {
             return .none  // First launch
         }
         
         // Step 2: Get pending notifications from UNUserNotificationCenter
-        let pendingRequests = try await notificationCenter.pendingNotificationRequests()
+        // Handle notification center errors gracefully (non-fatal)
+        let pendingRequests: [UNNotificationRequest]
+        do {
+            pendingRequests = try await notificationCenter.pendingNotificationRequests()
+        } catch {
+            // Non-fatal: Log error and assume no pending notifications
+            NSLog("\(Self.TAG): Error getting pending notifications (non-fatal): \(error.localizedDescription)")
+            // Return cold start as safe default - will trigger recovery
+            return .coldStart
+        }
+        
         let pendingIds = Set(pendingRequests.map { $0.identifier })
         
         // Step 3: Get notification IDs from storage
@@ -317,7 +335,15 @@ class DailyNotificationReactivationManager {
      */
     internal func detectMissedNotifications(currentTime: Date) async throws -> [NotificationContent] {
         // Get all notifications from storage
-        let allNotifications = storage.getAllNotifications()
+        // Handle database/storage errors gracefully (non-fatal)
+        let allNotifications: [NotificationContent]
+        do {
+            allNotifications = storage.getAllNotifications()
+        } catch {
+            // Non-fatal: Log error and return empty array
+            NSLog("\(Self.TAG): Error getting notifications from storage (non-fatal): \(error.localizedDescription)")
+            return []
+        }
         
         // Convert currentTime to milliseconds (Int64) for comparison
         let currentTimeMs = Int64(currentTime.timeIntervalSince1970 * 1000)
@@ -368,12 +394,46 @@ class DailyNotificationReactivationManager {
      */
     internal func verifyFutureNotifications() async throws -> VerificationResult {
         // Get pending notifications from UNUserNotificationCenter
-        let pendingRequests = try await notificationCenter.pendingNotificationRequests()
+        // Handle notification center errors gracefully (non-fatal)
+        let pendingRequests: [UNNotificationRequest]
+        do {
+            pendingRequests = try await notificationCenter.pendingNotificationRequests()
+        } catch {
+            // Non-fatal: Log error and assume no pending notifications
+            NSLog("\(Self.TAG): Error getting pending notifications (non-fatal): \(error.localizedDescription)")
+            // Return verification result indicating all are missing
+            let currentTimeMs = Int64(Date().timeIntervalSince1970 * 1000)
+            let allNotifications = storage.getAllNotifications()
+            let futureNotifications = allNotifications.filter { $0.scheduledTime >= currentTimeMs }
+            let futureIds = Set(futureNotifications.map { $0.id })
+            
+            return VerificationResult(
+                totalSchedules: futureNotifications.count,
+                notificationsFound: 0,
+                notificationsMissing: futureIds.count,
+                missingIds: Array(futureIds)
+            )
+        }
+        
         let pendingIds = Set(pendingRequests.map { $0.identifier })
         
         // Get all notifications from storage that are scheduled for future
+        // Handle storage errors gracefully (non-fatal)
         let currentTimeMs = Int64(Date().timeIntervalSince1970 * 1000)
-        let allNotifications = storage.getAllNotifications()
+        let allNotifications: [NotificationContent]
+        do {
+            allNotifications = storage.getAllNotifications()
+        } catch {
+            // Non-fatal: Log error and return empty verification result
+            NSLog("\(Self.TAG): Error getting notifications from storage (non-fatal): \(error.localizedDescription)")
+            return VerificationResult(
+                totalSchedules: 0,
+                notificationsFound: pendingIds.count,
+                notificationsMissing: 0,
+                missingIds: []
+            )
+        }
+        
         let futureNotifications = allNotifications.filter { $0.scheduledTime >= currentTimeMs }
         let futureIds = Set(futureNotifications.map { $0.id })
         
@@ -397,14 +457,27 @@ class DailyNotificationReactivationManager {
      */
     private func rescheduleMissingNotification(id: String) async throws {
         // Get notification content from storage
-        guard let notification = storage.getNotificationContent(id: id) else {
+        // Handle storage errors gracefully (non-fatal)
+        let notification: NotificationContent?
+        do {
+            notification = storage.getNotificationContent(id: id)
+        } catch {
+            // Non-fatal: Log error and throw to be caught by caller
+            NSLog("\(Self.TAG): Error getting notification from storage (non-fatal): \(error.localizedDescription)")
+            throw ReactivationError.notificationNotFound(id: id)
+        }
+        
+        guard let notification = notification else {
             throw ReactivationError.notificationNotFound(id: id)
         }
         
         // Reschedule using scheduler
+        // Handle scheduling errors gracefully (non-fatal)
         let success = await scheduler.scheduleNotification(notification)
         
         if !success {
+            // Non-fatal: Log error and throw to be caught by caller
+            NSLog("\(Self.TAG): Failed to reschedule notification \(id) (non-fatal)")
             throw ReactivationError.rescheduleFailed(id: id)
         }
     }