- Remove unused context.py module (replaced by request.state)
- Remove provider_cache.py (no longer needed)
- Unify environment loading in config/settings.py instead of __init__.py
- Add deprecation warning for get_async_db() (consolidating on sync Session)
- Enhance database.py documentation with comprehensive transaction strategy
- Simplify audit logging to reuse request-level Session (no separate connections)
- Extract UsageService._build_usage_params() helper to reduce code duplication
- Update model and user cache implementations with refined transaction handling
- Remove unnecessary sessionmaker from pipeline
- Clean up audit service exception handling
