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.
