Refactors date handling for ISO week compatibility

Centralizes all date calculations into a new `DateCalculator` class for better maintainability and consistency.

Ensures correct ISO week handling (Monday as the first day) throughout the calendar.

Updates `CalendarConfig` to use ISO day numbering (1-7 for Mon-Sun) for work week definitions.

Fixes issue where date calculations were inconsistent.
Enhances event rendering and navigation.
Updates navigation logic to use pre-rendered events.
Removes the need for `CONTAINER_READY_FOR_EVENTS` event.

src/factories/ManagerFactory.ts

@@ -42,7 +42,7 @@ export class ManagerFactory {
     const eventRenderer = new EventRenderingService(eventBus, eventManager);
     const gridManager = new GridManager();
     const scrollManager = new ScrollManager();
-    const navigationManager = new NavigationManager(eventBus);
+    const navigationManager = new NavigationManager(eventBus, eventRenderer);
     const viewManager = new ViewManager(eventBus);
     
     // CalendarManager depends on all other managers