refactor(NutritionalValue): improve value validation logic

Refactored the constructor to use strict comparison for value validation.

domain/Models/ValueObjects/Products/NutritionalValue.php

@@ -16,7 +16,7 @@ final readonly class NutritionalValue implements Arrayable, JsonSerializable
         public string $value,
         public NutritionnalUnit $unit
     ) {
-        if (empty(mb_trim($value))) {
+        if (mb_trim($value) === '') {
             throw new \DomainException('Value cannot be empty.');
         }
     }