slug-preserve - case-preserving slugifier.
Internal crate for fren. Public API is intentionally narrow: a single
[slugify] entry point plus a [SlugOpts] struct controlling separator
and case behavior.
Unlike the popular slug crate (and most other Rust slug crates) which
always lowercase, slug-preserve exposes a [CaseMode::Preserve] mode
that keeps the original character case intact, plus Lower, Upper,
Title, and Capitalize modes for explicit case control.