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/MonthViewStrategy.ts

@@ -142,6 +142,22 @@ export class MonthViewStrategy implements ViewStrategy {
     return this.getMonthDates(baseDate);
   }
   
+  getPeriodRange(baseDate: Date): { startDate: Date; endDate: Date } {
+    // Month view shows events for the entire month grid (including partial weeks)
+    const firstOfMonth = new Date(baseDate.getFullYear(), baseDate.getMonth(), 1);
+    
+    // Get Monday of the week containing first day
+    const startDate = this.dateCalculator.getISOWeekStart(firstOfMonth);
+    
+    // End date is 41 days after start (42 total days)
+    const endDate = this.dateCalculator.addDays(startDate, 41);
+    
+    return {
+      startDate,
+      endDate
+    };
+  }
+  
   destroy(): void {
     console.log('MonthViewStrategy: Cleaning up');
   }

src/strategies/ViewStrategy.ts

@@ -60,6 +60,11 @@ export interface ViewStrategy {
    */
   getDisplayDates(baseDate: Date): Date[];
   
+  /**
+   * Get the period start and end dates for event filtering
+   */
+  getPeriodRange(baseDate: Date): { startDate: Date; endDate: Date };
+  
   /**
    * Clean up any view-specific resources
    */

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