Add offline support for field data collection

[StencilwashCoder]

Problem

Coffee farms often have poor/no connectivity. Workers need to:

• Check in to shifts (scan QR)
• Record lot weights
• Take photos of harvest

Currently all these operations require immediate API connectivity. If offline, the app fails.

Use Case

Worker Maria scans QR to check in at 6am in a remote coffee field with no cell signal. The check-in should queue locally and sync when connectivity returns.

Suggested Implementation

• Add AsyncStorage or SQLite for local queue
• Create offline queue system for mutations (check-ins, lot creation)
• Show pending sync count in UI
• Background sync when app returns online
• Conflict resolution for duplicate check-ins

Data to Cache Offline

• Shift details (after first load)
• Worker profile
• Pending check-ins (queue until synced)
• Draft lot records with photos (sync when online)

UI Changes Needed

• Visual indicator when in offline mode
• "Syncing..." status with progress
• Retry button for failed syncs