Function assert_user_exit_ok

tests/integration/kernel_integration.rs:136–154

A hosted user program injected as pid 1 must spawn and exit with code 0.

(uart: &str, outcome: &StepOutcome, label: &str)

        uart.contains("[ PROC ] pid 1 ready"),
        "{label}: user process was not spawned; uart={uart:?}"
    );
    // A pid-1 program exiting cleanly calls kshutdown(0), halting the VM with 0.
    assert!(
        matches!(outcome, StepOutcome::Halted(0)),
        "{label}: user process did not exit cleanly with code 0; got {outcome:?}, uart={uart:?}"
    );
}

// Compile a hosted program and inject it as pid 1 (no FS image), then assert a
// clean spawn-and-exit.
fn run_example_in_kernel(user_src: &str, label: &str) {
    let user = compile_hosted(user_src);
    let (_, outcome, uart) = boot_kernel(cached_kernel(), Some(&user), None, "", 10_000_000);
    assert_user_exit_ok(&uart, &outcome, label);
}

fn run_example_manifest_in_kernel(name: &str) {
    let manifest_path = std::path::Path::new(env!("CARGO_MANIFEST_DIR"))
        .join("programs/example")
        .join(name)
        .join(format!("{name}.build"));
    let manifest = BuildManifest::from_file(&manifest_path)