(ui) Extend page headers across utility views

Apply the shared page-header pattern to configuration, access,
operations, retention, log, and changelog pages so the control panel
uses one consistent title, context, and action structure.

Add representative view assertions for the new page context on utility
pages.

Refs #28

src/pobsync_backend/tests/test_views.py

@@ -295,6 +295,7 @@ class ViewTests(TestCase):
 
         self.assertEqual(response.status_code, 200)
         self.assertContains(response, "Self Check")
+        self.assertContains(response, "Runtime, filesystem, service, and configuration checks")
         self.assertContains(response, "Django debug")
         self.assertContains(response, "Database connection")
         self.assertContains(response, "State root")
@@ -329,6 +330,7 @@ class ViewTests(TestCase):
 
         self.assertEqual(response.status_code, 200)
         self.assertContains(response, "Logs")
+        self.assertContains(response, "Filter pobsync service logs")
         self.assertContains(response, "web-01 failed backup run 12")
         self.assertNotContains(response, "web-02 failed backup run 12")
         self.assertNotContains(response, "started")
@@ -358,6 +360,7 @@ class ViewTests(TestCase):
 
         self.assertEqual(response.status_code, 200)
         self.assertContains(response, "Purged Snapshots")
+        self.assertContains(response, "Audit trail for snapshots removed")
         self.assertContains(response, "20260518-021500Z__OLDSNAP")
         self.assertContains(response, "outside retention policy")
         self.assertContains(response, "Scheduled")
@@ -412,6 +415,7 @@ class ViewTests(TestCase):
             )
 
         self.assertRedirects(response, reverse("ssh_credentials"))
+        self.assertContains(response, "Manage the key pairs pobsync uses")
         self.assertContains(response, "SSH credential saved for backup-key.")
         self.assertContains(response, "backup-key")
         credential = SshCredential.objects.get(name="backup-key")
@@ -641,6 +645,7 @@ class ViewTests(TestCase):
         response = self.client.get(reverse("edit_global_config"))
 
         self.assertEqual(response.status_code, 200)
+        self.assertContains(response, "Defaults used by hosts unless a host overrides them")
         self.assertContains(response, f'value="{credential.id}" selected')
         self.assertContains(response, "--archive")
         self.assertContains(response, "/proc/***")
@@ -2031,6 +2036,7 @@ class ViewTests(TestCase):
         response = self.client.get(reverse("edit_host_schedule", args=[host.host]))
 
         self.assertEqual(response.status_code, 200)
+        self.assertContains(response, "Automatic backup timing and scheduled prune behavior")
         self.assertContains(response, "Create Schedule")
         self.assertContains(response, "Schedule expression")
         self.assertContains(response, "evaluated by the pobsync scheduler service")