Module git 

Git operations for cgx

This module implements a two-tier git caching system inspired by cargo:

1. Git database cache (bare repositories) - one per URL
2. Git checkout cache (working trees) - one per commit

This architecture enables:

• Targeted refspec fetches which can be much more efficient for large repos
• Warm cache reuse when multiple commits from the same repo are used over time
• Correct handling of submodules, filters, and line endings via native gix checkout

Enums

GitSelector

Git reference selector for fetching specific refs.