Improves all-day event drag and drop

Handles dragging of both timed events (converting to all-day) and existing all-day events to different days.

Refactors all-day height recalculation to support animated transitions for a smoother user experience when all-day event counts change.

Uses event delegation for header mouseover detection.

Updates ScrollManager to listen for header height changes.

src/renderers/GridRenderer.ts

@@ -135,12 +135,30 @@ export class GridRenderer {
 
     headerRenderer.render(calendarHeader, context);
     
-    // Add mouseover listeners on day headers for drag detection
-    const dayHeaders = calendarHeader.querySelectorAll('swp-day-header');
-    dayHeaders.forEach(dayHeader => {
-      dayHeader.addEventListener('mouseover', () => {
-        eventBus.emit('header:mouseover', { dayHeader, headerRenderer });
-      });
+    // Use event delegation for mouseover detection on entire header
+    calendarHeader.addEventListener('mouseover', (event) => {
+      const target = event.target as HTMLElement;
+      
+      // Check what was hovered - could be day-header OR all-day-container
+      const dayHeader = target.closest('swp-day-header');
+      const allDayContainer = target.closest('swp-allday-container');
+      
+      if (dayHeader || allDayContainer) {
+        const hoveredElement = dayHeader || allDayContainer;
+        const targetDate = (hoveredElement as HTMLElement).dataset.date;
+        
+        console.log('GridRenderer: Detected hover over:', {
+          elementType: dayHeader ? 'day-header' : 'all-day-container',
+          targetDate,
+          element: hoveredElement
+        });
+        
+        eventBus.emit('header:mouseover', { 
+          element: hoveredElement,
+          targetDate,
+          headerRenderer 
+        });
+      }
     });
   }
 
@@ -179,7 +197,7 @@ export class GridRenderer {
     // Clear existing content
     calendarHeader.innerHTML = '';
 
-    // Re-render headers using Strategy Pattern
+    // Re-render headers using Strategy Pattern - this will also re-attach the event listener
     this.renderCalendarHeader(calendarHeader as HTMLElement, currentWeek, resourceData);
   }
 }