Fixes drag and drop to header issues

Addresses two key issues related to dragging events to the header: the premature removal of the original event element and the creation of duplicate all-day events.

The original event is no longer removed when dragging to the header; it is now only removed upon a successful drop.

Also, it prevents the creation of duplicate all-day events by checking for existing all-day events before creating new ones, using DOM queries to ensure accurate state.

src/managers/HeaderManager.ts

@@ -1,6 +1,9 @@
 import { eventBus } from '../core/EventBus';
 import { calendarConfig } from '../core/CalendarConfig';
 import { CalendarTypeFactory } from '../factories/CalendarTypeFactory';
+import { CoreEvents } from '../constants/CoreEvents';
+import { HeaderRenderContext } from '../renderers/HeaderRenderer';
+import { ResourceCalendarData } from '../types/CalendarTypes';
 
 /**
  * HeaderManager - Handles all header-related event logic
@@ -15,6 +18,16 @@ export class HeaderManager {
     // Bind methods for event listeners
     this.setupHeaderDragListeners = this.setupHeaderDragListeners.bind(this);
     this.destroy = this.destroy.bind(this);
+    
+    // Listen for navigation events to update header
+    this.setupNavigationListener();
+  }
+
+  /**
+   * Initialize header with initial date
+   */
+  public initializeHeader(currentDate: Date, resourceData: ResourceCalendarData | null = null): void {
+    this.updateHeader(currentDate, resourceData);
   }
 
   /**
@@ -98,6 +111,81 @@ export class HeaderManager {
     }
   }
 
+  /**
+   * Setup navigation event listener
+   */
+  private setupNavigationListener(): void {
+    eventBus.on(CoreEvents.NAVIGATION_COMPLETED, (event) => {
+      const { currentDate, resourceData } = (event as CustomEvent).detail;
+      this.updateHeader(currentDate, resourceData);
+    });
+
+    // Also listen for date changes (including initial setup)
+    eventBus.on(CoreEvents.DATE_CHANGED, (event) => {
+      const { currentDate } = (event as CustomEvent).detail;
+      this.updateHeader(currentDate, null);
+    });
+
+    // Listen for workweek header updates after grid rebuild
+    eventBus.on('workweek:header-update', (event) => {
+      const { currentDate } = (event as CustomEvent).detail;
+      this.clearCache(); // Clear cache since DOM was cleared
+      this.updateHeader(currentDate, null);
+    });
+
+  }
+
+  /**
+   * Update header content for navigation
+   */
+  private updateHeader(currentDate: Date, resourceData: ResourceCalendarData | null = null): void {
+    const calendarHeader = this.getOrCreateCalendarHeader();
+    if (!calendarHeader) return;
+
+    // Clear existing content
+    calendarHeader.innerHTML = '';
+
+    // Render new header content
+    const calendarType = calendarConfig.getCalendarMode();
+    const headerRenderer = CalendarTypeFactory.getHeaderRenderer(calendarType);
+    
+    const context: HeaderRenderContext = {
+      currentWeek: currentDate,
+      config: calendarConfig,
+      resourceData: resourceData
+    };
+
+    headerRenderer.render(calendarHeader, context);
+
+    // Re-setup event listeners
+    this.setupHeaderDragListeners();
+
+    // Notify other managers that header was rebuilt
+    eventBus.emit('header:rebuilt', {
+      headerElement: calendarHeader
+    });
+  }
+
+  /**
+   * Get or create calendar header element
+   */
+  private getOrCreateCalendarHeader(): HTMLElement | null {
+    let calendarHeader = this.getCalendarHeader();
+    
+    if (!calendarHeader) {
+      // Find grid container and create header
+      const gridContainer = document.querySelector('swp-grid-container');
+      if (gridContainer) {
+        calendarHeader = document.createElement('swp-calendar-header');
+        // Insert header as first child
+        gridContainer.insertBefore(calendarHeader, gridContainer.firstChild);
+        this.cachedCalendarHeader = calendarHeader;
+      }
+    }
+    
+    return calendarHeader;
+  }
+
   /**
    * Clear cached header reference
    */