refactor : reorganize codebase to DDD architecture

Backend:
- src/Api/Auth/State/ — MeProvider, UserPasswordHasherProcessor
- src/Api/Shared/Resource/ — AppVersion
- src/Api/Shared/State/ — AppVersionProvider
- src/Domain/, src/Application/, src/Infrastructure/ — skeleton ready
- User entity stays in src/Entity/ (framework, outside DDD)

Frontend:
- frontend/domains/ — skeleton ready for bounded contexts

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

src/Api/Auth/State/MeProvider.php

@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Api\Auth\State;
+
+use ApiPlatform\Metadata\Operation;
+use ApiPlatform\State\ProviderInterface;
+use Symfony\Bundle\SecurityBundle\Security;
+
+/**
+ * @implements ProviderInterface<\App\Entity\User>
+ */
+class MeProvider implements ProviderInterface
+{
+    public function __construct(
+        private readonly Security $security,
+    ) {}
+
+    public function provide(Operation $operation, array $uriVariables = [], array $context = []): ?object
+    {
+        return $this->security->getUser();
+    }
+}