fixed a small database issue with price drop tracking and added doc strings

src/monitor_utils/constants.py

@@ -1,3 +1,10 @@
+"""Shared constants for monitors and the consumer bot.
+
+Holds Mongo connection settings, bot tokens, retry and timeout tuning,
+client fingerprint identifiers, webhook routing maps, product status values,
+and the expected error tuple used for known-failure handling.
+"""
+
 import asyncio
 from json import JSONDecodeError