Add pre-commit hook to run clang-format on changed files

[bburda]

Summary

Add a pre-commit hook that automatically runs clang-format on the files changed in a commit, ensuring consistent C/C++ code formatting before code is pushed.

Proposed solution

Introduce pre-commit configuration (e.g., .pre-commit-config.yaml) in the repository.

• Add a hook that runs clang-format only on staged/changed files (C/C++ sources and headers, e.g. *.c, *.cc, *.cpp, *.cxx, *.h, *.hpp, *.hxx).
• Ensure the hook uses the project’s .clang-format file.
• Document setup in README.md (e.g., pip install pre-commit && pre-commit install) and how to run manually (e.g., pre-commit run -a).

Additional context

We could also consider extending pre-commit with flake8 and Python formatter.