Enhance test coverage to 100 %, and improve error handling -> 1.1.1

[molshape]

This pull request introduces several improvements and fixes to the casregnum package, including enhanced test coverage reporting, improved error handling, and documentation updates. The most significant changes are grouped below.

Continuous Integration and Coverage Reporting:

• Added branch coverage reporting to the test suite and integrated Codecov for uploading coverage reports in the CI workflow (.github/workflows/ci.yml).
• Added a Codecov badge to the README.md to display coverage status.

Documentation Improvements:

• Clarified installation and uninstallation instructions in the README.md, including usage of uv as an alternative to pip.
• Fixed minor typos and improved phrasing in the documentation, such as correcting "Table of Content" to "Table of Contents" and clarifying code output explanations. [1] [2] [3]

Code Quality and Error Handling:

• Improved type safety in the CAS class by making comparison methods (__eq__, __lt__) raise a TypeError when compared with non-CAS objects, instead of returning False or NotImplemented.
• Updated tests to explicitly check for raised exceptions (using pytest.raises) for invalid inputs and operations, replacing previous use of pytest.mark.xfail.

Internal Refactoring:

• Changed private attribute naming in the CAS class from double underscore (name mangling) to single underscore for clarity and consistency. [1] [2] [3] [4]
• Added from __future__ import annotations for forward type references, and reorganized imports for clarity. [1] [2] [3]

Version Update:

• Bumped the package version from 1.1.0 to 1.1.1 in pyproject.toml.

These changes collectively improve the reliability, maintainability, and clarity of the casregnum package.

[codecov-commenter]

Welcome to Codecov 🎉

Once you merge this PR into your default branch, you're all set! Codecov will compare coverage reports and display results in all future pull requests.

ℹ️ You can also turn on project coverage checks and project coverage reporting on Pull Request comment

Thanks for integrating Codecov - We've got you covered ☂️