feat: ingest burst hardening — defer lifecycle/auth, workers, nginx (v0.5.5)

Defer notify_lifecycle and notify_auth_login after commit; SAC_UVICORN_WORKERS via sac-api-start.sh; nginx /api/v1/events timeout; mass-update confirm in Hosts UI.

backend/tests/test_ingest.py

@@ -133,3 +133,48 @@ def test_ingest_daily_report_calls_notify_daily_report(client, auth_headers):
     mock_daily.assert_called_once()
     mock_event.assert_not_called()
 
+
+def test_ingest_lifecycle_defers_notify(client, auth_headers):
+    from unittest.mock import patch
+
+    from app.api.v1 import events as events_api
+
+    event_id = str(uuid.uuid4())
+    payload = {
+        **VALID_EVENT,
+        "event_id": event_id,
+        "type": "agent.lifecycle",
+        "title": "started",
+        "summary": "agent started",
+        "details": {"lifecycle": "started"},
+    }
+    with patch.object(events_api, "schedule_notify_lifecycle") as mock_defer:
+        with patch.object(events_api, "notify_lifecycle") as mock_sync:
+            r = client.post("/api/v1/events", json=payload, headers=auth_headers)
+    assert r.status_code == 201
+    mock_defer.assert_called_once()
+    mock_sync.assert_not_called()
+
+
+def test_ingest_auth_login_defers_notify(client, auth_headers):
+    from unittest.mock import patch
+
+    from app.api.v1 import events as events_api
+
+    event_id = str(uuid.uuid4())
+    payload = {
+        **VALID_EVENT,
+        "event_id": event_id,
+        "category": "auth",
+        "type": "ssh.login.success",
+        "severity": "info",
+        "title": "SSH login",
+        "summary": "user@host",
+    }
+    with patch.object(events_api, "schedule_notify_auth_login") as mock_defer:
+        with patch.object(events_api, "notify_auth_login") as mock_sync:
+            r = client.post("/api/v1/events", json=payload, headers=auth_headers)
+    assert r.status_code == 201
+    mock_defer.assert_called_once()
+    mock_sync.assert_not_called()
+