Address PR review feedback

- Gate e2e-admin superuser behind E2E_MODE env var (security)
- Add status and tag filters to ArticleFilterSet
- Set default_ordering to -published_date on listing viewset
- Add summary to ArticlePage.search_fields for search support
- Add 4 new tests for filters, ordering, and search fields

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

apps/blog/tests/test_admin_experience.py

@@ -232,3 +232,44 @@ def test_article_edit_page_has_tabbed_interface(client, django_user_model, home_
     assert "Metadata" in content
     assert "Publishing" in content
     assert "SEO" in content
+
+
+@pytest.mark.django_db
+@override_settings(ALLOWED_HOSTS=["testserver", "localhost", "127.0.0.1"])
+def test_articles_listing_has_status_filter(client, django_user_model, home_page):
+    """The Articles listing should accept status filter parameter."""
+    admin = django_user_model.objects.create_superuser(
+        username="admin", email="admin@example.com", password="admin-pass"
+    )
+    client.force_login(admin)
+    response = client.get("/cms/articles/?status=live")
+    assert response.status_code == 200
+
+
+@pytest.mark.django_db
+@override_settings(ALLOWED_HOSTS=["testserver", "localhost", "127.0.0.1"])
+def test_articles_listing_has_tag_filter(client, django_user_model, home_page):
+    """The Articles listing should accept tag filter parameter."""
+    admin = django_user_model.objects.create_superuser(
+        username="admin", email="admin@example.com", password="admin-pass"
+    )
+    client.force_login(admin)
+    response = client.get("/cms/articles/?tag=1")
+    assert response.status_code == 200
+
+
+@pytest.mark.django_db
+def test_article_listing_default_ordering():
+    """ArticlePageListingViewSet should default to -published_date ordering."""
+    from apps.blog.wagtail_hooks import ArticlePageListingViewSet
+
+    assert ArticlePageListingViewSet.default_ordering == "-published_date"
+
+
+@pytest.mark.django_db
+def test_article_search_fields_include_summary():
+    """ArticlePage.search_fields should index the summary field."""
+    field_names = [
+        f.field_name for f in ArticlePage.search_fields if hasattr(f, "field_name")
+    ]
+    assert "summary" in field_names