A Rust Crate, an R Package, and One Very Stubborn Windows Crash

I had never ported a Rust crate to R, and I wanted more control over link checking than I was getting. So I wrapped lychee with extendr. This is the whole trip: why I started outside CRAN on purpose, how you run async Rust from inside R, the Windows crash that took four attempts to fix, and an honest look at whether the result was actually worth it.