feat : WIP prix au kilo et prix total sur les bovins

- Champ pricePerKg persisté sur Bovine + migration
- Getter calculé finalPrice = receivedWeight * pricePerKg
- Colonnes Prix/kg et Prix total sur inventory et case
- Ajustements de largeurs pour rentrer dans le layout

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/Entity/Bovine.php

@@ -77,6 +77,10 @@ class Bovine
     #[Groups(['bovine:read', 'bovine:write', 'building_case:read'])]
     private ?int $receivedWeight = null;
 
+    #[ORM\Column(type: 'float', nullable: true)]
+    #[Groups(['bovine:read', 'bovine:write', 'building_case:read'])]
+    private ?float $pricePerKg = null;
+
     #[ORM\Column(type: 'date_immutable', nullable: true)]
     #[Groups(['bovine:read', 'bovine:write', 'building_case:read'])]
     #[Context([DateTimeNormalizer::FORMAT_KEY => 'Y-m-d'])]
@@ -151,6 +155,28 @@ class Bovine
         return $this;
     }
 
+    public function getPricePerKg(): ?float
+    {
+        return $this->pricePerKg;
+    }
+
+    public function setPricePerKg(?float $pricePerKg): static
+    {
+        $this->pricePerKg = $pricePerKg;
+
+        return $this;
+    }
+
+    #[Groups(['bovine:read', 'building_case:read'])]
+    public function getFinalPrice(): ?float
+    {
+        if (null === $this->receivedWeight || null === $this->pricePerKg) {
+            return null;
+        }
+
+        return $this->receivedWeight * $this->pricePerKg;
+    }
+
     public function getArrivalDate(): ?DateTimeImmutable
     {
         return $this->arrivalDate;