* refactor: codesplit CLI commands and interactive mode utils

- Added `commands.mjs` to define CLI commands including help, version, and interactive mode.
- Introduced `index.mjs` as the entry point for the CLI, handling argument parsing and command execution.
- Created utility functions for downloading files and validating output directories.
- Implemented interactive menu for rule selection, allowing users to choose rules dynamically.
- Updated test suite to cover new CLI functionalities and ensure robust error handling.

* chore: update CLI entry point to use index.mjs

* chore: remove CLI entry point file `cli.mjs`

* fix: correct output directory validation logic in CLI

- Moved the validation check for the output directory to occur before logging the start message.
- Updated tests to reflect changes in the CLI entry point from `cli.mjs` to `cli/index.mjs`, ensuring all commands are executed correctly.
- Removed outdated test file `cli.test.js` to streamline the test suite.