feat(commercial) : messages de validation FR sur les contraintes back + garde-fou (ERP-107)

Audit et complete les messages des contraintes #[Assert\*] des entites metier
(pendant back du mapping d'erreur par champ front ERP-101) :

- Message FR explicite sur toutes les contraintes (Email, NotBlank, Length,
  Bic, Iban, PositiveOrZero, Count...) des entites Client, ClientContact,
  ClientAddress, ClientRib, Category, Role, User.
- Ajout des Assert\Length manquantes calees sur le length de la colonne ORM
  (telephones VARCHAR(20), siren, nTva, accountNumber, username...) : evite
  une erreur Postgres 500 non rattachee au champ au profit d'une 422 propre.
- Locale FR globale (symfony/translation + default_locale: fr) comme filet
  pour les messages natifs non surcharges.
- Garde-fou tests/Architecture/EntityConstraintsHaveFrenchMessageTest : echoue
  si une contrainte n'a pas de message FR explicite ou si Assert\Length.max
  diverge du length ORM (whitelist justifiee pour les formats Bic/Iban/Regex).
- Test fonctionnel du JSON 422 reel (message FR + propertyPath consommable
  par useFormErrors cote front).
- Convention documentee dans .claude/rules/backend.md.

Tests : 469 verts (1793 assertions).

composer.lock

@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "aada2e60fd7563f1498b5505b37e3f4b",
+    "content-hash": "2dc5db01e7f5d6aecd5956749b21a092",
     "packages": [
         {
             "name": "api-platform/doctrine-common",
@@ -7657,6 +7657,99 @@
             ],
             "time": "2026-03-30T15:14:47+00:00"
         },
+        {
+            "name": "symfony/translation",
+            "version": "v8.0.10",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/symfony/translation.git",
+                "reference": "f63e9342e12646a57c91ef8a366a4f9d8e557b67"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/symfony/translation/zipball/f63e9342e12646a57c91ef8a366a4f9d8e557b67",
+                "reference": "f63e9342e12646a57c91ef8a366a4f9d8e557b67",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=8.4",
+                "symfony/polyfill-mbstring": "^1.0",
+                "symfony/translation-contracts": "^3.6.1"
+            },
+            "conflict": {
+                "nikic/php-parser": "<5.0",
+                "symfony/http-client-contracts": "<2.5",
+                "symfony/service-contracts": "<2.5"
+            },
+            "provide": {
+                "symfony/translation-implementation": "2.3|3.0"
+            },
+            "require-dev": {
+                "nikic/php-parser": "^5.0",
+                "psr/log": "^1|^2|^3",
+                "symfony/config": "^7.4|^8.0",
+                "symfony/console": "^7.4|^8.0",
+                "symfony/dependency-injection": "^7.4|^8.0",
+                "symfony/finder": "^7.4|^8.0",
+                "symfony/http-client-contracts": "^2.5|^3.0",
+                "symfony/http-kernel": "^7.4|^8.0",
+                "symfony/intl": "^7.4|^8.0",
+                "symfony/polyfill-intl-icu": "^1.21",
+                "symfony/routing": "^7.4|^8.0",
+                "symfony/service-contracts": "^2.5|^3",
+                "symfony/yaml": "^7.4|^8.0"
+            },
+            "type": "library",
+            "autoload": {
+                "files": [
+                    "Resources/functions.php"
+                ],
+                "psr-4": {
+                    "Symfony\\Component\\Translation\\": ""
+                },
+                "exclude-from-classmap": [
+                    "/Tests/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Fabien Potencier",
+                    "email": "fabien@symfony.com"
+                },
+                {
+                    "name": "Symfony Community",
+                    "homepage": "https://symfony.com/contributors"
+                }
+            ],
+            "description": "Provides tools to internationalize your application",
+            "homepage": "https://symfony.com",
+            "support": {
+                "source": "https://github.com/symfony/translation/tree/v8.0.10"
+            },
+            "funding": [
+                {
+                    "url": "https://symfony.com/sponsor",
+                    "type": "custom"
+                },
+                {
+                    "url": "https://github.com/fabpot",
+                    "type": "github"
+                },
+                {
+                    "url": "https://github.com/nicolas-grekas",
+                    "type": "github"
+                },
+                {
+                    "url": "https://tidelift.com/funding/github/packagist/symfony/symfony",
+                    "type": "tidelift"
+                }
+            ],
+            "time": "2026-05-06T11:30:54+00:00"
+        },
         {
             "name": "symfony/translation-contracts",
             "version": "v3.6.1",