Fix example backend asgi.py — import testapp.clients (was testapp.mizan_clients)

Discovery convention per MIZAN.md is `clients.py`. The example backend's
asgi.py was still importing the older `mizan_clients` name, causing the
example Django container to fail to start.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

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

@@ -9,6 +9,6 @@ from django.core.asgi import get_asgi_application
 from mizan import wrap_asgi
 
 # Register server functions and channels before building the ASGI app
-import testapp.mizan_clients  # noqa: F401
+import testapp.clients  # noqa: F401
 
 application = wrap_asgi(get_asgi_application())