feat: implement offline synchronization with mutation queue and background sync

- Created useOfflineSync hook for connectivity detection and sync management
- Implemented localStorage-based mutation queue for offline operations
- Added background sync support in service worker
- Created OfflineIndicator component to show connection status
- Added offline-aware action wrappers for seamless offline/online transitions
- Implemented conflict handling with retry logic (up to 3 retries)
- Auto-sync when connection is restored
- Validates Requirements 4.5

hooks/index.ts

@@ -8,3 +8,5 @@ export { useFilters } from './useFilters'
 export type { FilterState } from './useFilters'
 export { useOptimisticUpdate, useOptimisticList } from './useOptimisticUpdate'
 export { useScrollPosition, useContainerScrollPosition } from './useScrollPosition'
+export { useOfflineSync } from './useOfflineSync'
+export type { QueuedMutation } from './useOfflineSync'