feat : add project code and task auto-numbering

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

src/Repository/TaskRepository.php

@@ -4,6 +4,7 @@ declare(strict_types=1);
 
 namespace App\Repository;
 
+use App\Entity\Project;
 use App\Entity\Task;
 use Doctrine\Bundle\DoctrineBundle\Repository\ServiceEntityRepository;
 use Doctrine\Persistence\ManagerRegistry;
@@ -14,4 +15,17 @@ class TaskRepository extends ServiceEntityRepository
     {
         parent::__construct($registry, Task::class);
     }
+
+    public function findMaxNumberByProject(Project $project): int
+    {
+        $result = $this->createQueryBuilder('t')
+            ->select('MAX(t.number)')
+            ->where('t.project = :project')
+            ->setParameter('project', $project)
+            ->getQuery()
+            ->getSingleScalarResult()
+        ;
+
+        return (int) ($result ?? 0);
+    }
 }