add set scheduling api

backend/app/Schedule/CreateScheduleDto.php

@@ -0,0 +1,22 @@
+<?php
+
+namespace App\Schedule;
+
+use App\Set\Set;
+use App\User\User;
+use DateTimeImmutable;
+
+final readonly class CreateScheduleDto
+{
+    /**
+     * @param list<CreateScheduleAssignmentDto> $assignments
+     */
+    public function __construct(
+        public User $user,
+        public Set $set,
+        public string $elementKind,
+        public DateTimeImmutable $startDate,
+        public DateTimeImmutable $targetDate,
+        public array $assignments,
+    ) {}
+}