feat: split nights off an accommodation booking as separate periods

addresses #869f6z36v

tests/Form/Model/AccommodationBookingPeriodDtoTest.php

@@ -0,0 +1,46 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Tests\Form\Model;
+
+use App\Entity\Groups\AccommodationBookingPeriod;
+use App\Enum\Groups\AccommodationBookingPeriodPosition;
+use App\Form\Model\AccommodationBookingPeriodDto;
+use App\Form\Model\AccommodationBookingPeriodLineDto;
+use PHPUnit\Framework\TestCase;
+
+class AccommodationBookingPeriodDtoTest extends TestCase
+{
+    public function testTheEditModalStartsFromWhatThePeriodHolds(): void
+    {
+        $period = (new AccommodationBookingPeriod(
+            AccommodationBookingPeriodPosition::Leading,
+            new \DateTimeImmutable('2026-07-01'),
+            new \DateTimeImmutable('2026-07-03'),
+        ))
+            ->setLabel('Vorausteam')
+            ->setLines([['label' => 'Übernachtung', 'amount' => 25000]]);
+
+        $dto = AccommodationBookingPeriodDto::fromPeriod($period);
+
+        self::assertSame('Vorausteam', $dto->label);
+        self::assertSame(2, $dto->nights);
+        self::assertSame([['label' => 'Übernachtung', 'amount' => 25000]], $dto->linesSnapshot());
+    }
+
+    public function testTheLinesAreStoredAsAListWhateverKeysTheFormSubmitted(): void
+    {
+        // A collection form keeps the indexes of the rows it was sent, so after a removed row
+        // the keys have gaps — the JSON column must still get a list, not an object.
+        $dto = new AccommodationBookingPeriodDto(1, [
+            2 => new AccommodationBookingPeriodLineDto('Übernachtung', 25000),
+            5 => new AccommodationBookingPeriodLineDto('Verpflegung', 6000),
+        ]);
+
+        self::assertSame([
+            ['label' => 'Übernachtung', 'amount' => 25000],
+            ['label' => 'Verpflegung', 'amount' => 6000],
+        ], $dto->linesSnapshot());
+    }
+}