Portable metadata

Checks that reject tree shapes which work on one OS but break checkouts elsewhere.

Rule kinds in the Portable metadata family. Each rule below links to its own page with options, an example, and any auto-fix support.

Rule	Description
line_endings	Every line ending matches target: lf or crlf.
no_case_conflicts	Flag paths that differ only by case (e.g. README.md + readme.md).
no_illegal_windows_names	Reject path components that Windows cannot represent.
no_symlinks	Flag tracked paths that are symbolic links.