- New internal/fs package for testable filesystem operations
- In-memory filesystem support for unit testing without disk I/O
- Swappable global FS: SetFS(afero.NewMemMapFs())
- Wrapper functions: ReadFile, WriteFile, Mkdir, Walk, Glob, etc.
- Testing helpers: WithMemFs(), SetupTestDir()
- Comprehensive test suite demonstrating usage
- Upgraded afero from v1.10.0 to v1.15.0
