fix(sites) : add PATCH operation and fix migration constraint drop

Add Patch operation to Site entity (was only Put, causing 405 errors).
Fix migration to use ALTER TABLE DROP CONSTRAINT instead of DROP INDEX
for the piece name unique constraint.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/Entity/Site.php

@@ -8,6 +8,7 @@ use ApiPlatform\Metadata\ApiResource;
 use ApiPlatform\Metadata\Delete;
 use ApiPlatform\Metadata\Get;
 use ApiPlatform\Metadata\GetCollection;
+use ApiPlatform\Metadata\Patch;
 use ApiPlatform\Metadata\Post;
 use ApiPlatform\Metadata\Put;
 use App\Repository\SiteRepository;
@@ -28,6 +29,7 @@ use Symfony\Component\Validator\Constraints as Assert;
         new GetCollection(security: "is_granted('ROLE_VIEWER')"),
         new Post(security: "is_granted('ROLE_GESTIONNAIRE')"),
         new Put(security: "is_granted('ROLE_GESTIONNAIRE')"),
+        new Patch(security: "is_granted('ROLE_GESTIONNAIRE')"),
         new Delete(security: "is_granted('ROLE_GESTIONNAIRE')"),
     ],
     paginationClientItemsPerPage: true,