Improves grid navigation animation

Refactors grid navigation to improve the animation flow.

Removes the immediate clearing of events to prevent visual glitches during the slide animation.  Instead, events are now rendered directly into the new container without clearing.  This change ensures a smoother transition between grids.

Also, cleans up old grid elements after the animation completes, reducing DOM clutter.

src/renderers/EventRenderer.ts

@@ -22,8 +22,10 @@ export abstract class BaseEventRenderer implements EventRendererStrategy {
   renderEvents(events: CalendarEvent[], config: CalendarConfig): void {
     console.log('BaseEventRenderer: renderEvents called with', events.length, 'events');
     
-    // Clear existing events first
-    this.clearEvents();
+    // NOTE: Removed clearEvents() to support sliding animation
+    // With sliding animation, multiple grid containers exist simultaneously
+    // clearEvents() would remove events from all containers, breaking the animation
+    // Events are now rendered directly into the new container without clearing
 
     // Events should already be filtered by DataManager - no need to filter here
     console.log('BaseEventRenderer: Rendering', events.length, 'pre-filtered events');