Refactors calendar event rendering and management

Improves code organization and maintainability by separating concerns related to all-day event rendering, header management, and event resizing.

Moves all-day event rendering logic into a dedicated `AllDayEventRenderer` class, utilizing the factory pattern for event element creation.

Refactors `AllDayManager` to handle all-day row height animations, separated from `HeaderManager`.

Removes the `ResizeManager` and related functionality.

These changes aim to reduce code duplication, improve testability, and enhance the overall architecture of the calendar component.

src/renderers/GridRenderer.ts

@@ -154,8 +154,6 @@ export class GridRenderer {
 
     headerRenderer.render(calendarHeader, context);
     
-    // Always ensure all-day containers exist for all days
-    headerRenderer.ensureAllDayContainers(calendarHeader);
     
     // Setup only grid-related event listeners
     this.setupGridEventListeners();