Consolidates all-day event row limit

Centralizes the maximum number of displayed all-day event rows into a single constant.

This change ensures consistency and simplifies management of the all-day event row limit across the application.

Corrects off-by-one error in overflow count.

src/core/CalendarConfig.ts

@@ -12,6 +12,7 @@ export const ALL_DAY_CONSTANTS = {
   EVENT_HEIGHT: 22,    // Height of single all-day event
   EVENT_GAP: 2,        // Gap between stacked events
   CONTAINER_PADDING: 4, // Container padding (top + bottom)
+  MAX_COLLAPSED_ROWS: 4, // Show 4 rows when collapsed (3 events + 1 indicator row)
   get SINGLE_ROW_HEIGHT() {
     return this.EVENT_HEIGHT + this.EVENT_GAP; // 28px
   }