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/settings.py

@@ -0,0 +1,46 @@
+"""
+Django settings for running mizan's test suite standalone.
+
+Usage:
+    cd django/
+    pip install -e ".[dev]"
+    pytest
+"""
+
+SECRET_KEY = "test-secret-key-for-standalone-tests-only"
+
+DEBUG = True
+
+DATABASES = {
+    "default": {
+        "ENGINE": "django.db.backends.sqlite3",
+        "NAME": ":memory:",
+    }
+}
+
+INSTALLED_APPS = [
+    "django.contrib.auth",
+    "django.contrib.contenttypes",
+    "django.contrib.sessions",
+    "mizan",
+    "tests",
+]
+
+AUTH_USER_MODEL = "tests.EmailUser"
+
+ROOT_URLCONF = "tests.urls"
+
+DEFAULT_AUTO_FIELD = "django.db.models.BigAutoField"
+
+# JWT settings for test_auth.py (can be overridden per-class with @override_settings)
+JWT_PRIVATE_KEY = "test-secret-key-for-testing-only"
+JWT_ALGORITHM = "HS256"
+
+# Session engine (for test_auth.py SessionStore usage)
+SESSION_ENGINE = "django.contrib.sessions.backends.db"
+
+MIDDLEWARE = [
+    "django.contrib.sessions.middleware.SessionMiddleware",
+    "django.middleware.csrf.CsrfViewMiddleware",
+    "django.contrib.auth.middleware.AuthenticationMiddleware",
+]