feat: ajout entity OrderNumber pour la gestion des numeros de commande

src/Entity/OrderNumber.php (nouveau):
- id: int auto-increment
- numOrder: string(50) unique, le numero de commande
- createdAt: DateTimeImmutable, date de creation (auto dans le constructeur)
- isUsed: bool, false par defaut, marque via markAsUsed()

src/Repository/OrderNumberRepository.php (nouveau):
- Repository Doctrine standard pour OrderNumber

migrations/Version20260402201935.php:
- Table order_number avec index unique sur num_order
- created_at TIMESTAMP, is_used BOOLEAN

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

migrations/Version20260402201935.php

@@ -0,0 +1,32 @@
+<?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 Version20260402201935 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 order_number (id INT GENERATED BY DEFAULT AS IDENTITY NOT NULL, num_order VARCHAR(50) NOT NULL, created_at TIMESTAMP(0) WITHOUT TIME ZONE NOT NULL, is_used BOOLEAN NOT NULL, PRIMARY KEY (id))');
+        $this->addSql('CREATE UNIQUE INDEX UNIQ_551F0F81B2AA22EE ON order_number (num_order)');
+    }
+
+    public function down(Schema $schema): void
+    {
+        // this down() migration is auto-generated, please modify it to your needs
+        $this->addSql('DROP TABLE order_number');
+    }
+}