fix(templates): each delete page says what deleting its object does

The shared delete page asked only whether to delete the object. Each
view now gives its consequence: a deleted compute's VMs keep running
but the panel forgets them and their owners, a deleted user's VMs
stay, a group's members keep their accounts, a VM's owner loses only
the access, a removed VM's record no longer brings its owners back,
an SSH key stays on the VMs that have it, a flavor only goes as a
size template.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

webvirtcloud/tests/test_delete_pages.py

@@ -0,0 +1,40 @@
+"""Each delete page says what deleting its object does, besides naming it."""
+
+from accounts.models import UserInstance, UserSSHKey
+from computes.models import Compute
+from django.contrib.auth import get_user_model
+from django.contrib.auth.models import Group
+from django.test import TestCase
+from django.urls import reverse
+from instances.models import Flavor, Instance, InstanceTombstone
+from lxml import html
+
+KEY = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIGJ5dGVzLWZvci10aGUtZGVsZXRlLXBhZ2UtdGVzdA== page@example.com"
+
+
+class DeletePageTests(TestCase):
+    def test_every_delete_page_says_what_deleting_does(self):
+        admin = get_user_model().objects.create_superuser("del-admin", "da@example.com", "pw")
+        user = get_user_model().objects.create_user("del-user", password="pw")
+        compute = Compute.objects.create(name="del-host", hostname="192.0.2.9", login="u", password="p", type=1)
+        vm = Instance.objects.create(compute=compute, name="del-vm", uuid="d0000000-0000-4000-8000-000000000001")
+        pages = {
+            reverse("compute_delete", args=[compute.id]): "the panel forgets them and who owns them",
+            reverse("admin:user_delete", args=[user.id]): "the VMs themselves stay",
+            reverse("admin:group_delete", args=[Group.objects.create(name="del-group").id]): "lose the permissions",
+            reverse("admin:tombstone_delete", args=[InstanceTombstone.objects.create(uuid=vm.uuid, name="gone").id]):
+                "no longer get the VM back",
+            reverse("accounts:user_instance_delete", args=[UserInstance.objects.create(user=user, instance=vm).id]):
+                "the VM itself is not changed",
+            reverse("instances:flavor_delete", args=[Flavor.objects.create(label="del-flavor", memory=512, vcpu=1, disk=1).id]):
+                "VMs made from it keep their size",
+        }
+        key = UserSSHKey.objects.create(user=admin, keyname="del-key", keypublic=KEY)
+        pages[reverse("accounts:ssh_key_delete", args=[key.id])] = "VMs that already have it keep it"
+        self.client.force_login(admin)
+        for url, consequence in pages.items():
+            with self.subTest(url=url):
+                alert = html.fromstring(self.client.get(url).content).xpath("//div[contains(@class, 'alert-warning')]")
+                self.assertEqual(len(alert), 1)
+                self.assertIn(consequence, alert[0].text_content())
+                self.assertNotIn("Are you sure", alert[0].text_content())