- Added Sprint type and interface
- Updated Task to include sprintId
- Added sprint actions to task store (addSprint, updateSprint, deleteSprint, selectSprint)
- Updated API to handle sprints
- Updated all sync calls to include sprints
- Added /api/tasks endpoint with file-based JSON storage
- Store now syncs from server on page load
- All changes auto-sync to server
- Added loading indicator while syncing
- Falls back to localStorage if server unavailable
- Tasks #8 now marked as done
