pub fn pkgs_dir(root: &Path) -> PkgDirExpand description
Where a project’s installed deps go: <root>/.htl/modules, always.
One directory, named in one place. htl does not read the location out of the
environment and does not infer it from whether target/ happens to exist — it decides
it here and hands it to mlua-pkg when it runs one (htl pkg), so the installer and the
checker cannot name different directories.
What goes on inside is mlua-pkg’s: mlua_pkg::PkgDir derives cache/ and
vendored/ from the base, and this returns one so htl does not spell that layout out a
second time. The one directory htl adds beside them is ENTRIES_DIR.