refactor: reorganize project structure and update module imports (#2112)

* refactor: reorganize project structure and update module imports
* configure setuptools to use 'src' layout and adjust package discovery
* refactor: move tests to `tests` directory and update imports accordingly
* update lint and mypy configurations to align with `src` and `tests` structure
* update test imports to use corrected `tests.helpers` module path
* fix(pre_commit): 🎨 auto format pre-commit hooks