tests: fix ruff warnings in minimal conftest

tests/conftest.py

@@ -0,0 +1,28 @@
+"""Minimal test session cleanup to prevent hanging background servers.
+
+This keeps the test suite simple while ensuring any stray embedding server
+processes are terminated at session start and end.
+"""
+
+import subprocess
+
+
+def _kill_embedding_servers() -> None:
+    patterns = [
+        "hnsw_embedding_server",
+        "diskann_embedding_server",
+        "embedding_server",
+    ]
+    for pat in patterns:
+        try:
+            subprocess.run(["pkill", "-9", "-f", pat], timeout=2, capture_output=True)
+        except Exception:
+            pass
+
+
+def pytest_sessionstart(session):
+    _kill_embedding_servers()
+
+
+def pytest_sessionfinish(session, exitstatus):
+    _kill_embedding_servers()