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.

config/modules.php

@@ -9,6 +9,7 @@ declare(strict_types=1);
 
 use App\Module\Absence\AbsenceModule;
 use App\Module\Core\CoreModule;
+use App\Module\Directory\DirectoryModule;
 use App\Module\ProjectManagement\ProjectManagementModule;
 use App\Module\TimeTracking\TimeTrackingModule;
 
@@ -17,4 +18,5 @@ return [
     TimeTrackingModule::class,
     ProjectManagementModule::class,
     AbsenceModule::class,
+    DirectoryModule::class,
 ];