feat: live последние события на Dashboard; retention, health, runbook

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

backend/tests/test_dashboard.py

@@ -90,3 +90,19 @@ def test_dashboard_summary_top_and_problems_24h(client, db_session, jwt_headers)
     types = {row["type"]: row["count"] for row in body["top_event_types"]}
     assert types["ssh.login.failed"] == 3
     assert types["agent.heartbeat"] == 2
+
+
+def test_dashboard_recent_events_ordered_by_received_at(client, db_session, jwt_headers):
+    h = _host(db_session, "live-host")
+    now = datetime.now(timezone.utc)
+    older = _event(db_session, h, "agent.lifecycle", received_at=now - timedelta(minutes=5))
+    newer = _event(db_session, h, "agent.heartbeat", received_at=now)
+    db_session.commit()
+
+    r = client.get("/api/v1/dashboards/recent-events?limit=8", headers=jwt_headers)
+    assert r.status_code == 200
+    rows = r.json()
+    assert len(rows) >= 2
+    assert rows[0]["id"] == newer.id
+    assert rows[0]["type"] == "agent.heartbeat"
+    assert rows[1]["id"] == older.id