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/Domain/Repository/ClientRepositoryInterface.php

@@ -0,0 +1,20 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Module\Directory\Domain\Repository;
+
+use App\Module\Directory\Domain\Entity\Client;
+
+interface ClientRepositoryInterface
+{
+    public function findById(int $id): ?Client;
+
+    /**
+     * @param array<string, mixed>       $criteria
+     * @param null|array<string, string> $orderBy
+     *
+     * @return Client[]
+     */
+    public function findBy(array $criteria, ?array $orderBy = null, ?int $limit = null, ?int $offset = null): array;
+}