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-desktop-app/backend/models.py

@@ -0,0 +1,15 @@
+from django.db import models
+
+
+class Note(models.Model):
+    title = models.CharField(max_length=200)
+    content = models.TextField(blank=True, default="")
+    pinned = models.BooleanField(default=False)
+    created_at = models.DateTimeField(auto_now_add=True)
+    updated_at = models.DateTimeField(auto_now=True)
+
+    class Meta:
+        ordering = ["-pinned", "-updated_at"]
+
+    def __str__(self):
+        return self.title