* Introduce SQLNames struct to define stored procedure names.
* Update DatabaseAuthenticator, JWTAuthenticator, and other providers to use SQLNames for procedure calls.
* Remove hardcoded procedure names for better flexibility and customization.
* Implement validation for SQL names to ensure they are valid identifiers.
* Add tests for SQLNames functionality and merging behavior.
* Implement TwoFactorAuthenticator for 2FA login.
* Create DatabaseTwoFactorProvider for PostgreSQL integration.
* Add MemoryTwoFactorProvider for in-memory testing.
* Develop TOTPGenerator for generating and validating codes.
* Include tests for all new functionalities.
* Ensure backup codes are securely hashed and validated.