feat: normalize email addresses to lowercase on write

tests/Entity/ContactTest.php

@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Tests\Entity;
+
+use App\Entity\Contact;
+use PHPUnit\Framework\TestCase;
+
+class ContactTest extends TestCase
+{
+    /**
+     * Office contacts are normalized the same way User::setEmail() normalizes, so that every
+     * stored address has one shape regardless of which form wrote it.
+     */
+    public function testSetEmailNormalizesCaseAndSurroundingWhitespace(): void
+    {
+        $contact = (new Contact())->setEmail('  [email protected] ');
+
+        $this->assertSame('[email protected]', $contact->getEmail());
+    }
+}