Add source_site_id to ActiveSite model and implement unique constraint. Update serializers and views for site registration and claiming. Enhance tests for site registration and claiming functionality.

backend/apps/accounts/tests_scoping.py

@@ -92,17 +92,22 @@ class VisibilityScopeTests(TestCase):
         self.assertEqual(response.data["results"], [])
 
     def test_registering_active_site_attaches_matching_seed_site(self):
+        ActiveSite.objects.create(
+            code="orphan-seed",
+            name="Orphan Seed",
+            api_base_url="https://orphan.example/api/v1",
+            api_key="k",
+            managed_by=None,
+        )
         self.client.force_authenticate(self.gm)
         response = self.client.post(
             "/api/v1/active-sites/",
             {
                 "code": "orphan-seed",
-                "name": "Orphan Seed",
-                "is_active": True,
             },
             format="json",
         )
-        self.assertEqual(response.status_code, 201)
+        self.assertEqual(response.status_code, 200, response.data)
         self.orphan.refresh_from_db()
         self.assertEqual(self.orphan.active_site_id, response.data["id"])
         listed = self.client.get("/api/v1/sites/")