feat: entité DomainEmail liée à Domain avec migration

Entity DomainEmail :
- domain (ManyToOne, CASCADE) : domaine parent
- name : partie locale de l'email (lowercase auto, ex: contact)
- state : active/suspended/disabled (défaut active)
- quotaMb : quota en Mo (défaut 5120 = 5 Go)
- createdAt / updatedAt : timestamps (updatedAt auto sur setState)
- getFullEmail() : retourne name@domain.fqdn
- isActive() : vérifie si state === active

DomainEmailTest (3 tests, 19 assertions) :
- testConstructor : valeurs par défaut, name lowercase/trim, fullEmail
- testSetters : name, quotaMb, updatedAt
- testState : active→suspended→disabled, updatedAt mis à jour

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

migrations/Version20260403220445.php

@@ -0,0 +1,34 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DoctrineMigrations;
+
+use Doctrine\DBAL\Schema\Schema;
+use Doctrine\Migrations\AbstractMigration;
+
+/**
+ * Auto-generated Migration: Please modify to your needs!
+ */
+final class Version20260403220445 extends AbstractMigration
+{
+    public function getDescription(): string
+    {
+        return '';
+    }
+
+    public function up(Schema $schema): void
+    {
+        // this up() migration is auto-generated, please modify it to your needs
+        $this->addSql('CREATE TABLE domain_email (id INT GENERATED BY DEFAULT AS IDENTITY NOT NULL, name VARCHAR(255) NOT NULL, state VARCHAR(20) NOT NULL, quota_mb INT NOT NULL, created_at TIMESTAMP(0) WITHOUT TIME ZONE NOT NULL, updated_at TIMESTAMP(0) WITHOUT TIME ZONE DEFAULT NULL, domain_id INT NOT NULL, PRIMARY KEY (id))');
+        $this->addSql('CREATE INDEX IDX_34E954A2115F0EE5 ON domain_email (domain_id)');
+        $this->addSql('ALTER TABLE domain_email ADD CONSTRAINT FK_34E954A2115F0EE5 FOREIGN KEY (domain_id) REFERENCES domain (id) ON DELETE CASCADE NOT DEFERRABLE');
+    }
+
+    public function down(Schema $schema): void
+    {
+        // this down() migration is auto-generated, please modify it to your needs
+        $this->addSql('ALTER TABLE domain_email DROP CONSTRAINT FK_34E954A2115F0EE5');
+        $this->addSql('DROP TABLE domain_email');
+    }
+}