Function setup_with_destinations_and_srcs 

pub fn setup_with_destinations_and_srcs(
    opts: &SetupOpts,
    dsts: &BTreeMap<String, PathBuf>,
    srcs: &BTreeMap<String, PathBuf>,
    prompter: &mut dyn Prompter,
    git: &dyn GitConfig,
) -> Result<SetupReport, SetupError>

Full entry point with both destination and source paths.

srcs maps section name → template source path for generic_template sections. Other writers ignore srcs.