Introduce an automatic formatting step in llm-commit to ensure that generated commit messages adhere to common best practices regarding line lengths, particularly:

• Subject line ≤ 50 characters
• Body lines wrapped at 72 characters
  This behavior should be enabled by default.

Problem

Currently, llm-commit may generate well-structured commit messages, but it doesn't guarantee adherence to formatting conventions regarding line lengths. For instance:

Current output example:

chore(makefile): enhance CSS build output readability

Improved the readability of the generated CSS files by expanding their style format. This change aids in debugging and maintenance by providing a clearer view of the CSS structure.

* Added `--style=expanded` option to the `npx sass` command in the Makefile
* Ensures that the generated CSS is more human-readable, facilitating easier troubleshooting and updates

This leads to long, hard-to-read lines, especially in terminal-based workflows.

A correct formatting should give :

chore(makefile): enhance CSS build output readability

Improved the readability of the generated CSS files by expanding their
style format. This change aids in debugging and maintenance by providing
a clearer view of the CSS structure.

* Added `--style=expanded` option to the `npx sass` command in the
  Makefile
* Ensures that the generated CSS is more human-readable, facilitating
  easier troubleshooting and updates

Proposed solution

1. Add a default post-processing step to format the commit message body:
   • Wrap body lines at 72 characters.
   • Optionally warn if the subject line exceeds 50 characters.
2. Use the mdformat library to perform Markdown-aware formatting, preserving lists and code blocks.

References

• StackOverflow: Git Commit Message Formatting (50/72)
• mdformat documentation