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/DataFixtures/AppFixtures.php

@@ -4,7 +4,6 @@ declare(strict_types=1);
 
 namespace App\DataFixtures;
 
-use App\Entity\Client;
 use App\Entity\MailConfiguration;
 use App\Entity\ZimbraConfiguration;
 use App\Enum\ContractType;
@@ -15,6 +14,7 @@ use App\Module\Absence\Domain\Enum\AbsenceStatus;
 use App\Module\Absence\Domain\Enum\AbsenceType;
 use App\Module\Core\Application\Rbac\RbacSeeder;
 use App\Module\Core\Domain\Entity\User;
+use App\Module\Directory\Domain\Entity\Client;
 use App\Module\ProjectManagement\Domain\Entity\Project;
 use App\Module\ProjectManagement\Domain\Entity\Task;
 use App\Module\ProjectManagement\Domain\Entity\TaskEffort;