Function install_mod 

pub async fn install_mod(
    base: &Path,
    eco: &Ecosystem,
    index: &PackageIndex,
    client: &ThunderstoreClient,
    game: &str,
    profile_name: &str,
    full_name: &str,
    installed_at_time: u64,
) -> Result<Vec<String>>

Installs a mod and its full dependency closure into an r2modman-layout profile, using base as both the profile base and the package cache base (matching this pipeline’s pre-existing behavior). See install_mod_in.