feat: normalize email addresses to lowercase on write

src/BusProNet/Model/Communication.php

@@ -39,7 +39,9 @@ class Communication
 
     public function setEmail(?string $email): static
     {
-        $this->email = $email;
+        // BusPro compares addresses case-insensitively; normalize on the way in so the DTO
+        // carries the same shape the entities store.
+        $this->email = null === $email ? null : mb_strtolower(trim($email));
 
         return $this;
     }