Restructure repo into five-package AFI architecture

Mizan is an Application Framework Interface (AFI) with five
independent packages:

  packages/
    mizan-ast/       Language layer (source → KDL schema)
    mizan-schema/    IR layer (KDL schema definition)
    mizan-rpc/       Protocol layer (client gen + server adapters)
      adapters/django/   ← was django/
      generator/         ← was react/src/generator/
    mizan-csr/       State layer (client state engine)
      adapters/react/    ← was react/
    mizan-ssr/       Rendering layer (server-side rendering)

Each package is independent. The adapter directories contain the
framework-specific implementations. Stub packages (ast, schema, ssr)
establish the structure for future work.

264 Django tests + 33 React tests pass from new locations.

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

packages/mizan-rpc/adapters/django/tests/models.py

@@ -0,0 +1,142 @@
+from django.contrib.auth.models import (
+    AbstractBaseUser,
+    BaseUserManager,
+    PermissionsMixin,
+)
+from django.db import models
+
+
+class EmailUserManager(BaseUserManager):
+    """Custom user manager using email as the unique identifier."""
+
+    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):
+    """Minimal user model with email as USERNAME_FIELD.
+
+    Matches the calling convention used in mizan's test suite:
+        User.objects.create_user(email="...", password="...", is_staff=True)
+    """
+
+    email = models.EmailField(unique=True)
+    is_staff = models.BooleanField(default=False)
+    is_active = models.BooleanField(default=True)
+
+    objects = EmailUserManager()
+
+    USERNAME_FIELD = "email"
+    REQUIRED_FIELDS = []
+
+    class Meta:
+        app_label = "tests"
+
+
+# ─── Shape test models ──────────────────────────────────────────────────────
+
+import uuid
+
+
+class TimestampMixin(models.Model):
+    created_at = models.DateTimeField(auto_now_add=True)
+    updated_at = models.DateTimeField(auto_now=True)
+
+    class Meta:
+        abstract = True
+
+
+class Publisher(TimestampMixin):
+    name = models.CharField(max_length=200)
+    country = models.CharField(max_length=100, default="")
+
+    class Meta:
+        app_label = "tests"
+
+
+class Author(TimestampMixin):
+    name = models.CharField(max_length=200)
+    bio = models.TextField(default="")
+    publisher = models.ForeignKey(
+        Publisher, on_delete=models.CASCADE, related_name="authors"
+    )
+    mentor = models.ForeignKey(
+        "self", on_delete=models.SET_NULL, null=True, blank=True, related_name="mentees"
+    )
+
+    class Meta:
+        app_label = "tests"
+
+
+class Tag(models.Model):
+    slug = models.SlugField(primary_key=True, max_length=100)
+    label = models.CharField(max_length=100)
+
+    class Meta:
+        app_label = "tests"
+
+
+class Book(TimestampMixin):
+    title = models.CharField(max_length=300)
+    isbn = models.CharField(max_length=13, unique=True)
+    page_count = models.IntegerField(default=0)
+    is_published = models.BooleanField(default=False)
+    author = models.ForeignKey(Author, on_delete=models.CASCADE, related_name="books")
+    editor = models.ForeignKey(
+        Author,
+        on_delete=models.SET_NULL,
+        null=True,
+        blank=True,
+        related_name="edited_books",
+    )
+    tags = models.ManyToManyField(Tag, blank=True, related_name="books")
+
+    class Meta:
+        app_label = "tests"
+
+
+class Chapter(TimestampMixin):
+    book = models.ForeignKey(Book, on_delete=models.CASCADE, related_name="chapters")
+    number = models.IntegerField()
+    title = models.CharField(max_length=300)
+    word_count = models.IntegerField(default=0)
+
+    class Meta:
+        app_label = "tests"
+        ordering = ["number"]
+        unique_together = [("book", "number")]
+
+
+class Section(models.Model):
+    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
+    chapter = models.ForeignKey(
+        Chapter, on_delete=models.CASCADE, related_name="sections"
+    )
+    heading = models.CharField(max_length=300)
+    body = models.TextField(default="")
+    position = models.IntegerField(default=0)
+
+    class Meta:
+        app_label = "tests"
+        ordering = ["position"]
+
+
+class Category(models.Model):
+    name = models.CharField(max_length=200)
+    parent = models.ForeignKey(
+        "self", on_delete=models.CASCADE, null=True, blank=True, related_name="children"
+    )
+
+    class Meta:
+        app_label = "tests"