extend User entity with displayname and email confirmation

Add display_name (unique) and email_confirmed_at columns plus
matching getters, DTO fields, repo methods (findByDisplayName,
update), and migration. Existing auth tests updated to construct
User with the new params.

backend/tests/Fakes/FakeUserRepository.php

@@ -6,6 +6,7 @@ use App\Shared\ValueObject\EmailAddress;
 use App\User\CreateUserDto;
 use App\User\User;
 use App\User\UserRepository;
+use RuntimeException;
 
 class FakeUserRepository implements UserRepository
 {
@@ -20,12 +21,14 @@ class FakeUserRepository implements UserRepository
         $user = new User(
             id: $id,
             email: $dto->email,
+            displayName: $dto->displayName,
             passwordHash: $dto->passwordHash,
             isAdmin: $dto->isAdmin,
+            emailConfirmedAt: $dto->emailConfirmedAt,
         );
         $this->existingUsers[$id] = $user;
 
-        return $user;
+        return $this->copy($user);
     }
 
     public function find(int $id): ?User
@@ -35,30 +38,59 @@ class FakeUserRepository implements UserRepository
             return null;
         }
 
-        return new User(
-            id: $user->getId(),
-            email: $user->getEmail(),
-            passwordHash: $user->getPasswordHash(),
-            isAdmin: $user->isAdmin(),
-        );
+        return $this->copy($user);
     }
 
     public function findByEmail(EmailAddress $email): ?User
     {
         foreach ($this->existingUsers as $user) {
             if ($user->getEmail()->equals($email)) {
-                return new User(
-                    id: $user->getId(),
-                    email: $user->getEmail(),
-                    passwordHash: $user->getPasswordHash(),
-                    isAdmin: $user->isAdmin(),
-                );
+                return $this->copy($user);
             }
         }
 
         return null;
     }
 
+    public function findByDisplayName(string $displayName): ?User
+    {
+        foreach ($this->existingUsers as $user) {
+            if ($user->getDisplayName() === $displayName) {
+                return $this->copy($user);
+            }
+        }
+
+        return null;
+    }
+
+    /**
+     * @throws RuntimeException
+     */
+    public function update(User $user): User
+    {
+        $id = $user->getId();
+        if (! isset($this->existingUsers[$id])) {
+            throw new RuntimeException(
+                "User with id: $id does not exist"
+            );
+        }
+        $this->existingUsers[$id] = $user;
+
+        return $this->copy($user);
+    }
+
+    private function copy(User $user): User
+    {
+        return new User(
+            id: $user->getId(),
+            email: $user->getEmail(),
+            displayName: $user->getDisplayName(),
+            passwordHash: $user->getPasswordHash(),
+            isAdmin: $user->isAdmin(),
+            emailConfirmedAt: $user->getEmailConfirmedAt(),
+        );
+    }
+
     private function getNextId(): int
     {
         return count($this->existingUsers) + 1;

backend/tests/Unit/Auth/Middleware/AuthMiddlewareTest.php

@@ -58,13 +58,15 @@ class AuthMiddlewareTest extends TestCase
         };
     }
 
-    private function makeUser(int $id = 7): User
+    private function makeUser(int $id): User
     {
         return new User(
             id: $id,
             email: new EmailAddress('user@example.com'),
+            displayName: 'user',
             passwordHash: 'hashed:irrelevant',
             isAdmin: false,
+            emailConfirmedAt: null,
         );
     }
 
@@ -100,7 +102,7 @@ class AuthMiddlewareTest extends TestCase
     {
         $this->sessionRepo->create(new CreateSessionDto(
             token: 'expired-token',
-            user: $this->makeUser(),
+            user: $this->makeUser(7),
             createdAt: $this->now->modify('-8 days'),
             expiresAt: $this->now->modify('-1 day'),
         ));

backend/tests/Unit/Auth/UseCases/CreateSessionTest.php

@@ -46,8 +46,10 @@ class CreateSessionTest extends TestCase
         return new User(
             id: 7,
             email: new EmailAddress('user@example.com'),
+            displayName: 'user',
             passwordHash: 'hashed:irrelevant',
             isAdmin: false,
+            emailConfirmedAt: null,
         );
     }
 

backend/tests/Unit/Auth/UseCases/LogoutTest.php

@@ -34,8 +34,10 @@ class LogoutTest extends TestCase
         $user = new User(
             id: 7,
             email: new EmailAddress('user@example.com'),
+            displayName: 'user',
             passwordHash: 'hashed:irrelevant',
             isAdmin: false,
+            emailConfirmedAt: null,
         );
         $this->sessionRepo->create(new CreateSessionDto(
             token: 'token-abc',