add set scheduling api

backend/app/Schedule/ScheduleAssignment.php

@@ -0,0 +1,36 @@
+<?php
+
+namespace App\Schedule;
+
+use App\Element\Element;
+use DateTimeImmutable;
+
+final readonly class ScheduleAssignment
+{
+    public function __construct(
+        private int $id,
+        private Element $element,
+        private DateTimeImmutable $scheduledDate,
+        private int $position,
+    ) {}
+
+    public function getId(): int
+    {
+        return $this->id;
+    }
+
+    public function getElement(): Element
+    {
+        return $this->element;
+    }
+
+    public function getScheduledDate(): DateTimeImmutable
+    {
+        return $this->scheduledDate;
+    }
+
+    public function getPosition(): int
+    {
+        return $this->position;
+    }
+}