Refactors calendar type to calendar mode

Updates the codebase to utilize `CalendarMode` instead of the deprecated `CalendarType`.

Simplifies `CalendarConfig` by removing legacy methods and related type aliases, enhancing code maintainability and clarity.

Improves event rendering by ensuring `GRID_RENDERED` events include explicit start and end dates, preventing errors and ensuring correct data filtering.

src/strategies/WeekViewStrategy.ts

@@ -67,6 +67,16 @@ export class WeekViewStrategy implements ViewStrategy {
     return this.dateCalculator.getWorkWeekDates(baseDate);
   }
   
+  getPeriodRange(baseDate: Date): { startDate: Date; endDate: Date } {
+    const weekStart = this.dateCalculator.getISOWeekStart(baseDate);
+    const weekEnd = this.dateCalculator.addDays(weekStart, 6);
+    
+    return {
+      startDate: weekStart,
+      endDate: weekEnd
+    };
+  }
+  
   destroy(): void {
     // Clean up any week-specific resources
     // For now, just log