feat: allow to edit existing relative reminders

src/modelTypes/ITaskReminder.ts

@@ -2,7 +2,7 @@ import type { IAbstract } from './IAbstract'
 import type { IReminderPeriodRelativeTo } from '@/types/IReminderPeriodRelativeTo'
 
 export interface ITaskReminder extends IAbstract {
-	reminder: Date
+	reminder: Date | null
 	relativePeriod: number
-	relativeTo: IReminderPeriodRelativeTo
+	relativeTo: IReminderPeriodRelativeTo | null
 }