feat: env management

[dat-adi]

The current model relies on environment variables needing to be present in the instance of the shell. This is a practice that works for initial testing, but a better alternative would be to extend upon the application to incorporate reading files for initializing the settings instead.

1. Start.
2. Import secrets from config/settings.rs.
3. settings.rs checks for the value of the variables in both the shell and the config.toml file.
4. Application is run successfully.

References -> 1, 2.