fix: set QDRANT_URL/COLLECTION_NAME env vars for test import

tests/test_server.py

@@ -1,5 +1,9 @@
 """Unit tests for mcp-maildir server pure functions."""
 
+import os
+os.environ["QDRANT_URL"] = "http://localhost:6333"
+os.environ["COLLECTION_NAME"] = "test"
+
 from server import (
     normalize_email_address,
     payload_matches_participant,