Integrate Hydra or OmegaConf for robust configuration and environment variable management

[hanaol]

We should integrate a configuration management library, such as Hydra or OmegaConf, to:

1. Load configuration files and environment variables consistently.

2. Validate configuration values to prevent invalid or mistyped settings.

3. Make it easier to manage different training setups and experiments.

This improvement will enhance maintainability and reduce potential errors in experiment configuration.

Originally posted by @hanaol in #26 (comment)