- Created sync client for communicating with API server
- Implemented conflict resolution strategies (last-write-wins, server-wins, client-wins)
- Added offline change queue for queuing changes when server is unreachable
- Implemented merge logic for local and remote task lists
- Added conflict logging to sync_conflicts.log
- Created bidirectional sync with pull/push operations
- Extended Config struct with sync settings (URL, API key, client ID, strategy, offline queue)
- Added SyncResult display with user-friendly output
- Sync handlers already implemented in Phase 1 (GetChanges, PushChanges)
- Add WeekStartDay and DefaultDueTime fields to Config struct
- Set defaults: week_start_day=monday, default_due_time=empty
- Add GetWeekStart() and GetDefaultDueTime() helper methods
- Update ParseDate() to use configured week start day
- All tests passing