Adds expanded state tracking for header drawer during drag
Ensures drawer remains in the correct expanded/collapsed state based on initial condition
Improves user experience by maintaining consistent drawer state
Introduces HeaderDrawerRenderer and HeaderDrawerLayoutEngine to support dragging events into an all-day header drawer
Enables dynamic event placement and conversion between timed and all-day events through new drag interactions
Implements flexible layout calculation for header items with column and row management
Extends DragDropManager to handle header zone interactions
Adds new event types for header drag events
