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/managers/NavigationManager.ts

@@ -158,19 +158,27 @@ export class NavigationManager {
       (currentGrid as HTMLElement).style.transform = direction === 'next' ? 'translateX(-100%)' : 'translateX(100%)';
       (currentGrid as HTMLElement).style.opacity = '0.5';
       
+      // Cleanup: Remove all old grids except the new one after animation
+      setTimeout(() => {
+        const allGrids = container.querySelectorAll('swp-grid-container');
+        // Keep only the newest grid (last one), remove all others
+        for (let i = 0; i < allGrids.length - 1; i++) {
+          allGrids[i].remove();
+        }
+      }, 450);
+      
       // Slide in new grid
       newGrid.style.transform = 'translateX(0)';
       
-      // Clean up after animation (POC cleanup)
+      // Wait for new grid animation to complete before updating state
       setTimeout(() => {
-        currentGrid.remove();
         newGrid.style.position = 'relative';
         
-        // Update currentWeek only after animation is complete (POC logic)
+        // Only now is the animation truly complete
         this.currentWeek = new Date(targetWeek);
         this.animationQueue--;
         
-        // If this was the last queued animation, ensure we're in sync (POC sync)
+        // If this was the last queued animation, ensure we're in sync
         if (this.animationQueue === 0) {
           this.currentWeek = new Date(this.targetWeek);
         }
@@ -183,7 +191,7 @@ export class NavigationManager {
         });
         
         console.log(`NavigationManager: Completed ${direction} animation`);
-      }, 400); // Match POC timing
+      }, 400); // Wait for slide-in animation to complete
     });
   }