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/urls.py

@@ -0,0 +1,5 @@
+from django.urls import include, path
+
+urlpatterns = [
+    path("api/mizan/", include("mizan.urls")),
+]