- Add OfflineSyncCoordinator for managing offline/online transitions
- Add OfflineSyncIndicatorView for UI feedback during sync
- Add SyncProgress tracking with stage descriptions and progress bars
- Add delta sync support with savings tracking
- Add BackgroundTaskScheduler interval configs for low-power mode
- Add isProcessingTask discriminator to BackgroundTaskID
- Add DeltaFetchResult generic type for efficient data fetching
- Add SyncProgressStage enum with localized descriptions
- Add progress reset on app launch to prevent stale state
- Add delta sync savings percentage calculation
- Update BackgroundSyncTests with comprehensive coverage
- Add OfflineSyncTests for offline queue and conflict resolution
- Mark task 22 (Token Refresh) and task 28 (Review Compliance) as done
- Update Xcode project with new source files and build phases
- Add KordantSpamShieldExtension target to project.yml with proper
app-extension type, bundle identifier, and deployment target
- Create CallKit + App Group entitlements for SpamShield extension
- Move SpamDirectoryService to Sources/Shared for cross-target access
- Update app-review-checklist with 5 new technical items (total: 121)
- Update rejection-risk-mitigation with extension build integration
- Add SpamShield extension details to reviewer notes
- Mark Task 24 (push deep links) and Task 28 as complete
