fix: Remove unused imports (F401 lint errors)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: keitaj

tests/test_ws_market_data_feed.py

@@ -3,7 +3,7 @@
 import time
 from unittest.mock import MagicMock, patch
 
-from market_data import MarketDataManager, MarketData
+from market_data import MarketDataManager
 from ttl_cache import TTLCacheMap
 from ws.market_data_feed import MarketDataFeed
 

ws/market_data_feed.py

@@ -16,7 +16,7 @@
 import logging
 import threading
 import time
-from typing import Any, Dict, List, Optional
+from typing import Any, Dict, List
 
 logger = logging.getLogger(__name__)