test: mark integration suite with pytest.mark.integration

Required for -m 'not integration' to actually deselect them (pytest.ini
addopts) and for 'pytest -m integration' in the nightly CI job.

tests/test_integration.py

@@ -11,6 +11,10 @@ os.environ["EMBEDDING_MODEL_NAME"] = "BAAI/bge-small-en-v1.5"
 from server import get_qdrant_client, get_embedding_model, search_emails, read_email
 from qdrant_client.http import models
 
+# Requires a live Qdrant on localhost:6333 (see pytest.ini: deselected by
+# default; run with `pytest -m integration`, nightly CI does exactly that).
+pytestmark = pytest.mark.integration
+
 
 TEST_EMAILS = [
     {