Cargo failing at gitignore-d files while publishing

Finally managed to find a workaround for the Rust problem I was having with cargo publish picking up files from my gitignore-d .direnv directory and complaining about them being uncommitted.

This was the result of cascading surprises: setting package.includes causes gitignore to no longer be considered, and "README.md" in package.includes actually works like "**/README.md"’ and picks up the READMEs from the repositories in .direnv/flake-inputs/.

Upstream issue: https://github.com/rust-lang/cargo/issues/12294#issuecomment-2171044946