feat(directory) : add Prospect entity with conversion to Client (back)

LST-58 (2.4), part 2 — Prospect (new entity). Completes the Directory backend.

- ProspectStatus enum (new/contacted/qualified/won/lost) + Prospect entity
  (name, company, email, phone, address, status, source, notes,
  convertedClient -> ClientInterface) with Timestampable/Blamable + #[Auditable].
- API: GetCollection/Get (ROLE_USER), Post/Patch/Delete (ROLE_ADMIN),
  custom POST /prospects/{id}/convert (ConvertProspectProcessor: creates a
  Client from the prospect, links convertedClient, sets status=Won; idempotent).
  SearchFilter on status.
- Repository interface + Doctrine impl (bound); 6 MCP tools (list/get/create/
  update/delete/convert-prospect); Serializer::prospect(). Module perms
  directory.prospects.view/manage. Demo fixtures (3 prospects, one converted).
- Additive migration: CREATE TABLE prospect + FKs ON DELETE SET NULL + COMMENT.

163 tests green (incl. conversion test), mapping valid, cs-fixer clean.

tests/Functional/Module/Directory/ProspectConversionTest.php

@@ -0,0 +1,77 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Tests\Functional\Module\Directory;
+
+use ApiPlatform\Metadata\Post;
+use App\Module\Directory\Domain\Entity\Prospect;
+use App\Module\Directory\Domain\Enum\ProspectStatus;
+use App\Module\Directory\Infrastructure\ApiPlatform\State\ConvertProspectProcessor;
+use App\Module\Directory\Infrastructure\Doctrine\DoctrineProspectRepository;
+use Doctrine\ORM\EntityManagerInterface;
+use Symfony\Bundle\FrameworkBundle\Test\KernelTestCase;
+
+/**
+ * @internal
+ */
+class ProspectConversionTest extends KernelTestCase
+{
+    private EntityManagerInterface $em;
+
+    protected function setUp(): void
+    {
+        self::bootKernel();
+        $this->em = self::getContainer()->get(EntityManagerInterface::class);
+    }
+
+    public function testConvertCreatesClientAndFlagsProspectWon(): void
+    {
+        $prospect = new Prospect();
+        $prospect->setName('Lead Test');
+        $prospect->setCompany('Lead Company '.uniqid());
+        $prospect->setEmail('lead@example.com');
+        $prospect->setPhone('06 00 00 00 00');
+        $prospect->setStreet('1 rue du Test');
+        $prospect->setCity('Testville');
+        $prospect->setPostalCode('00000');
+        $prospect->setStatus(ProspectStatus::Qualified);
+        $this->em->persist($prospect);
+        $this->em->flush();
+
+        $result = $this->processor()->process($prospect, new Post(), ['id' => $prospect->getId()]);
+
+        self::assertSame(ProspectStatus::Won, $result->getStatus());
+        $client = $result->getConvertedClient();
+        self::assertNotNull($client);
+        self::assertSame($prospect->getCompany(), $client->getName());
+    }
+
+    public function testConvertIsIdempotent(): void
+    {
+        $prospect = new Prospect();
+        $prospect->setName('Idempotent Lead');
+        $prospect->setStatus(ProspectStatus::New);
+        $this->em->persist($prospect);
+        $this->em->flush();
+
+        $processor = $this->processor();
+        $first     = $processor->process($prospect, new Post(), ['id' => $prospect->getId()]);
+        $clientId  = $first->getConvertedClient()?->getId();
+
+        $second = $processor->process($prospect, new Post(), ['id' => $prospect->getId()]);
+
+        self::assertNotNull($clientId);
+        self::assertSame($clientId, $second->getConvertedClient()?->getId());
+    }
+
+    private function processor(): ConvertProspectProcessor
+    {
+        $c = self::getContainer();
+
+        return new ConvertProspectProcessor(
+            $c->get(EntityManagerInterface::class),
+            $c->get(DoctrineProspectRepository::class),
+        );
+    }
+}