feat(commercial) : validation back de la relation + suivi de revue MR (ERP-119)

- validation serveur « relation choisie => FK obligatoire » : champ transitoire
  relationType (non persiste) + Assert\Callback portant la 422 sur distributor /
  broker, que le back ne pouvait pas deriver des seules FK nullable
- mutualisation des payloads d'ecriture clients : new.vue consomme buildMainPayload
  / buildAddressPayload / buildRibPayload (fin de la duplication create/edit)
- COMMENT ON TABLE client_address : ajout des types Courtier / Distributeur
  (catalogue + migration Version20260609120000)
- tests : violationsByPath remonte dans AbstractCommercialApiTestCase (fin des
  copies inline) + couverture de la nouvelle RG relation

tests/Module/Commercial/Api/ClientSubResourceApiTest.php

@@ -89,10 +89,7 @@ final class ClientSubResourceApiTest extends AbstractCommercialApiTestCase
         ]);
 
         self::assertResponseStatusCodeSame(422);
-        $byPath = [];
-        foreach ($response->toArray(false)['violations'] ?? [] as $v) {
-            $byPath[$v['propertyPath']] = $v['message'];
-        }
+        $byPath = $this->violationsByPath($response->toArray(false));
 
         self::assertArrayHasKey('email', $byPath, 'La violation email doit porter propertyPath=email (mapping front).');
         self::assertSame('L\'adresse email n\'est pas valide.', $byPath['email']);
@@ -135,10 +132,7 @@ final class ClientSubResourceApiTest extends AbstractCommercialApiTestCase
         ]);
 
         self::assertResponseStatusCodeSame(422);
-        $byPath = [];
-        foreach ($response->toArray(false)['violations'] ?? [] as $v) {
-            $byPath[$v['propertyPath']] = $v['message'];
-        }
+        $byPath = $this->violationsByPath($response->toArray(false));
         self::assertArrayHasKey('email', $byPath);
         self::assertSame('L\'adresse email n\'est pas valide.', $byPath['email']);
     }
@@ -386,10 +380,7 @@ final class ClientSubResourceApiTest extends AbstractCommercialApiTestCase
         ]);
 
         self::assertResponseStatusCodeSame(422);
-        $byPath = [];
-        foreach ($response->toArray(false)['violations'] ?? [] as $v) {
-            $byPath[$v['propertyPath']] = $v['message'];
-        }
+        $byPath = $this->violationsByPath($response->toArray(false));
 
         self::assertArrayHasKey('bic', $byPath, 'Le mismatch pays BIC/IBAN doit porter propertyPath=bic (mapping front).');
         self::assertSame('Le BIC ne correspond pas au pays de l\'IBAN.', $byPath['bic']);