* ♻️ Refactor backend, update DB session handling
* ✨ Add mypy config and plugins
* ➕ Use Python-jose instead of PyJWT
as it has some extra functionalities and features
* ✨ Add/update scripts for test, lint, format
* 🔧 Update lint and format configs
* 🎨 Update import format, comments, and types
* 🎨 Add types to config
* ✨ Add types for all the code, and small fixes
* 🎨 Use global imports to simplify exploring with Jupyter
* ♻️ Import schemas and models, instead of each class
* 🚚 Rename db_session to db for simplicity
* 📌 Update dependencies installation for testing
