feat: Add originalStartTime to event DTOs and service to correctly identify and manage event exceptions in the UI.

admin/src/app/features/calendar/models/events-in-range-dto.model.ts

@@ -16,7 +16,7 @@ export type BookingWithUserDto = {
   id: number;
 };
 
-export interface EventExceptionDto{
+export interface EventExceptionDto {
   id: number,
   description: string;
   eventId: number;
@@ -33,6 +33,7 @@ export type CalendarEventDto = {
   id: number;
   title: string;
   startTime: string,
+  originalStartTime: string,
   endTime: string,
   description: string,
   isModified?: boolean;