feat(directory) : migrate Client into Directory module (back)

LST-58 (2.4), part 1/2 — Client move. Prospect + repertoire front are pending
the product spec and will be added on this branch afterward.

- Client entity moved to src/Module/Directory/Domain/Entity; repository split
  into Domain/Repository/ClientRepositoryInterface + Doctrine impl (bound in
  services.yaml). 5 client MCP tools moved to Infrastructure/Mcp/Tool, now
  injecting the interface.
- resolve_target_entities ClientInterface repointed to Directory\Client;
  Directory mapping added; DirectoryModule registered (id directory, 2 RBAC
  perms). Client.projects relation now uses ProjectInterface -> Directory no
  longer depends on ProjectManagement.
- ProjectManagement Create/UpdateProjectTool inject Directory's
  ClientRepositoryInterface; Serializer and fixtures repointed.
- Garde-fous: #[Auditable] + Timestampable/Blamable on Client (additive
  migration: created_at/updated_at + created_by/updated_by FK ON DELETE SET
  NULL + COMMENT).

161 tests green, mapping valid, no API route regression, cs-fixer clean.

src/Module/Directory/Infrastructure/Doctrine/DoctrineClientRepository.php

@@ -0,0 +1,26 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Module\Directory\Infrastructure\Doctrine;
+
+use App\Module\Directory\Domain\Entity\Client;
+use App\Module\Directory\Domain\Repository\ClientRepositoryInterface;
+use Doctrine\Bundle\DoctrineBundle\Repository\ServiceEntityRepository;
+use Doctrine\Persistence\ManagerRegistry;
+
+/**
+ * @extends ServiceEntityRepository<Client>
+ */
+final class DoctrineClientRepository extends ServiceEntityRepository implements ClientRepositoryInterface
+{
+    public function __construct(ManagerRegistry $registry)
+    {
+        parent::__construct($registry, Client::class);
+    }
+
+    public function findById(int $id): ?Client
+    {
+        return $this->find($id);
+    }
+}