feat: host display_name в ingest, поиск хостов, UI и docs

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/tests/test_health_ops.py

@@ -0,0 +1,11 @@
+"""Extended /health payload for ops monitoring."""
+
+
+def test_health_includes_stale_and_last_event(client, db_session, auth_headers):
+    r = client.get("/health")
+    assert r.status_code == 200
+    body = r.json()
+    assert body["database"] == "ok"
+    assert "hosts_stale" in body
+    assert "last_event_received_at" in body
+    assert body["service"] == "security-alert-center"