style: apply black and isort formatting across entire codebase

- Standardize quote style (single to double quotes)
- Reorder and group imports alphabetically
- Fix line breaks and indentation for consistency
- Apply PEP 8 formatting standards

Also updated Makefile to exclude both venv and .venv from code quality checks.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/utils/database.py

@@ -7,6 +7,7 @@ This module provides utility functions and classes to interact with a database u
 """
 
 import logging
+
 from sqlalchemy import create_engine
 from sqlalchemy.orm import sessionmaker
 from sqlalchemy.pool import QueuePool