* Refactor chat.py for improved readability and maintainability
* Add imports and fix formatting issues
* Refactor database connection in Alembic env.py
* Add nullable columns to tables and fix foreign key constraint
* Update sqlalchemy logging level to DEBUG in alembic.ini
* Add connection and inspector objects for database reflection
* Refactor alembic initialization and migration process
* Refactor version option in main_entry_point function
* Remove pre-commit hook and format code
* Fix database inspector type hinting
* Add unique constraints and fix credential table