Add CodeLimit workflow

[robvanderleek]

Thanks for this wonderful project.
Are you open to include a simple code quality check in the automated build system?
I'm developing an open source tool called CodeLimit that monitors function length.
Still in active development, looking for any kind of feedback from the community.
The generated report for this codebase is attached below.

CodeLimit Report

Overview

Language	Files	Lines of Code	Functions	⚠	❌
Python	14	734	96	3	0

Summary

Easy / Verbose	Hard-to-maintain ⚠	Unmaintainable ❌
85%	15%	0%

✅ 85% of the functions are maintainable, no refactoring necessary.

Findings

Function	Length	File
⚠ quickstart	38	twtxt/cli.py
⚠ timeline	36	twtxt/cli.py
⚠ build_default_map	32	twtxt/config.py