feat(sync) : add version field and PieceProductSlot entity

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

src/Entity/Composant.php

@@ -130,6 +130,10 @@ class Composant
     #[ORM\OrderBy(['position' => 'ASC'])]
     private Collection $productSlots;
 
+    #[ORM\Column(type: Types::INTEGER, options: ['default' => 1])]
+    #[Groups(['composant:read'])]
+    private int $version = 1;
+
     #[ORM\Column(type: Types::DATETIME_IMMUTABLE, name: 'createdAt')]
     #[Groups(['composant:read'])]
     private DateTimeImmutable $createdAt;
@@ -406,4 +410,16 @@ class Composant
 
         return $this;
     }
+
+    public function getVersion(): int
+    {
+        return $this->version;
+    }
+
+    public function incrementVersion(): static
+    {
+        ++$this->version;
+
+        return $this;
+    }
 }