add email signup flow

backend/app/User/User.php

@@ -4,12 +4,12 @@ namespace App\User;
 
 use App\Shared\ValueObject\EmailAddress;
 
-final readonly class User
+final class User
 {
     public function __construct(
         private int $id,
         private EmailAddress $email,
-        private string $passwordHash,
+        private ?string $passwordHash,
     ) {}
 
     public function getId(): int
@@ -22,8 +22,13 @@ final readonly class User
         return $this->email;
     }
 
-    public function getPasswordHash(): string
+    public function getPasswordHash(): ?string
     {
         return $this->passwordHash;
     }
+
+    public function setPasswordHash(string $passwordHash): void
+    {
+        $this->passwordHash = $passwordHash;
+    }
 }