add Python type hints and enable mypy checks (#335)

[DevPatel-11]

• Added type hints to CLI entry point (cli.py) and hello command
• Annotated all test functions in cli/test_cli.py with -> None
• Added mypy.ini configuration for stricter type checks
• Updated CI workflow to run mypy checks during linting

This improves overall code quality and maintainability by ensuring static type safety.

What type of PR is this? (check all applicable)

• ♻️ Refactor
• ✨ New Chapter
• 🐛 Bug Fix/Typo
• 👷 Optimization
• 📝 Documentation Update
• 🚩 Other

Description

This PR adds Python type hints across the CLI codebase and integrates mypy into the linting process.

Key changes:

• Added type hints to cli/cli.py and cli/commands/hello.py.
• Updated cli/test_cli.py:
  • All test functions now explicitly return -> None.
  • Annotated subprocess.run results with CompletedProcess[str].
• Introduced requirements/dev.txt with mypy as a dev dependency.
• Added mypy.ini config with strict checking (disallow_untyped_defs = True).
• Updated CI workflow to run mypy checks alongside linting.

This improves code quality, readability, and maintainability by ensuring type safety across the project.

Related Tickets & Documents

• Resolves Add type hints and mypy checks #335

Added to documentation?

• 📜 readme
• 🙅 no documentation needed

[optional] What gif best describes this PR or how it makes you feel?

[Copilot]

Pull Request Overview

This PR adds Python type hints to the CLI codebase and integrates mypy static type checking to improve code quality and maintainability. The changes include adding type annotations to core CLI modules and configuring mypy checks in the development workflow.

• Added type hints and docstrings to CLI entry points and commands
• Enhanced test reliability by adding check=True parameter to subprocess calls
• Introduced mypy as a development dependency with strict type checking configuration

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
cli/cli.py	Added docstring, main() function with type hint, and improved code organization
cli/commands/hello.py	Added module-level docstring for documentation
cli/test_cli.py	Enhanced subprocess.run calls with check=True parameter for better error handling
cli/requirements.txt	Added click dependency specification

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[Copilot]

The if __name__ == "__main__": block should call the new main() function instead of app() directly to maintain consistency with the defined entry point.

Suggested change

	app()
	main()