Adds IndexedDB and operation queue for robust offline synchronization
Introduces SyncManager to handle background data synchronization
Supports local event operations with automatic remote sync queuing
Enhances application reliability and user experience in low/no connectivity scenarios
Refactors the event layout and stacking logic based on review feedback.
This includes:
- Merging conflicting event groups to prevent inconsistencies.
- Implementing minimal stack level assignment using a min-heap.
- Consolidating styling and using DateService for drag operations.
- Adding reflow after drag and drop.
- Improving the column event filtering to include events overlapping midnight.
- Ensuring explicit sorting of events for grid layout.
