feature: a minimal implementation of the appointment feature done.

backend/src/modules/appointments/dto/list-appointments.dto.ts

@@ -0,0 +1,12 @@
+import { ApiProperty } from '@nestjs/swagger';
+import { IsDateString } from 'class-validator';
+
+export class ListAppointmentsDto {
+  @ApiProperty({ description: 'Range start (ISO 8601), e.g. local midnight as instant' })
+  @IsDateString()
+  from: string;
+
+  @ApiProperty({ description: 'Range end (ISO 8601), e.g. next local midnight' })
+  @IsDateString()
+  to: string;
+}