Improves all-day drag-and-drop conversion

Refactors drag-to-all-day functionality to apply CSS styling and reposition the existing drag clone within the all-day container, rather than creating a new event element.

Centralizes all-day container creation in HeaderManager. Introduces `drag:mouseleave-header` to handle transitions from all-day back to timed events.

Ensures consistent styling and robust cleanup of drag clones for a smoother user experience.

src/managers/HeaderManager.ts

@@ -24,6 +24,9 @@ export class HeaderManager {
     
     // Listen for navigation events to update header
     this.setupNavigationListener();
+    
+    // Listen for requests to ensure all-day container
+    this.setupContainerRequestListener();
   }
 
   /**
@@ -95,18 +98,23 @@ export class HeaderManager {
   }
 
   /**
-   * Ensure all-day container exists in header
+   * Ensure all-day container exists in header - creates directly
    */
-  private ensureAllDayContainer(): void {
+  private ensureAllDayContainer(): HTMLElement | null {
     const calendarHeader = this.getCalendarHeader();
-    if (!calendarHeader) return;
+    if (!calendarHeader) return null;
     
-    let allDayContainer = calendarHeader.querySelector('swp-allday-container');
+    let allDayContainer = calendarHeader.querySelector('swp-allday-container') as HTMLElement;
     
     if (!allDayContainer) {
-      console.log('📍 HeaderManager: All-day container missing, requesting creation...');
-      eventBus.emit('allday:ensure-container');
+      console.log('📍 HeaderManager: Creating all-day container directly...');
+      allDayContainer = document.createElement('swp-allday-container');
+      calendarHeader.appendChild(allDayContainer);
+    
+      console.log('✅ HeaderManager: All-day container created');
     }
+    
+    return allDayContainer;
   }
 
 
@@ -134,6 +142,16 @@ export class HeaderManager {
 
   }
 
+  /**
+   * Setup listener for all-day container creation requests
+   */
+  private setupContainerRequestListener(): void {
+    eventBus.on('header:ensure-allday-container', () => {
+      console.log('📍 HeaderManager: Received request to ensure all-day container');
+      this.ensureAllDayContainer();
+    });
+  }
+
   /**
    * Update header content for navigation
    */