fix: Resolve Ruff E402 warnings and clean up imports across multiple modules

models/performance_metric.py

@@ -1,7 +1,6 @@
 from __future__ import annotations
 
 from datetime import datetime
-from typing import Optional
 
 from sqlalchemy import Column, DateTime, Float, Integer, String
 from sqlalchemy.ext.declarative import declarative_base

models/pricing_settings.py

@@ -1,7 +1,7 @@
-from __future__ import annotations
-
 """Database models for persisted pricing configuration settings."""
 
+from __future__ import annotations
+
 from datetime import datetime
 from typing import TYPE_CHECKING