Move desktop and e2e into examples/ directory

- desktop/ → examples/django-react-desktop-app/
- e2e/ → examples/django-react-site/
- example/ → examples/django-react-site/backend/
- Update Dockerfile.test, Makefile, playwright config, and
  django.config.mjs path references

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

examples/django-react-site/backend/testapp/models.py

@@ -0,0 +1,29 @@
+from django.contrib.auth.models import AbstractBaseUser, BaseUserManager, PermissionsMixin
+from django.db import models
+
+
+class EmailUserManager(BaseUserManager):
+    def create_user(self, email, password=None, **extra_fields):
+        if not email:
+            raise ValueError("Email is required")
+        email = self.normalize_email(email)
+        user = self.model(email=email, **extra_fields)
+        user.set_password(password)
+        user.save(using=self._db)
+        return user
+
+    def create_superuser(self, email, password=None, **extra_fields):
+        extra_fields.setdefault("is_staff", True)
+        extra_fields.setdefault("is_superuser", True)
+        return self.create_user(email, password, **extra_fields)
+
+
+class EmailUser(AbstractBaseUser, PermissionsMixin):
+    email = models.EmailField(unique=True)
+    is_staff = models.BooleanField(default=False)
+    is_active = models.BooleanField(default=True)
+
+    objects = EmailUserManager()
+
+    USERNAME_FIELD = "email"
+    REQUIRED_FIELDS = []