node:util: implement aborted AbortSignal promise helper #3426

Summary

util.aborted(signal, resource) should return a Promise that settles when an AbortSignal aborts. Perry currently rejects the helper at compile time as an unimplemented node:util API.

Node Behavior

Minimal repro:

import * as util from "node:util";

const controller = new AbortController();
const promise = util.aborted(controller.signal, {});
console.log("aborted typeof:", typeof util.aborted);
console.log("promise:", promise instanceof Promise);

promise.then((event: any) => {
  console.log("resolved event:", event?.type, event?.target === controller.signal);
});

controller.abort("done");
await promise;

Node v25.9.0 prints:

aborted typeof: function
promise: true
resolved event: abort true

Perry Behavior

A focused parity probe in test-files/tmp_util_aborted.ts fails to compile:

Error: `util.aborted` is not implemented in Perry — see `perry --print-api-manifest` for the supported surface, or set `PERRY_ALLOW_UNIMPLEMENTED=1` to ignore. (#463)

Report: test-parity/reports/parity_report_20260530_104857.json.

This is listed in the broad util helper tracker #2514, but it belongs with the focused AbortSignal helper work rather than unrelated util formatting/debug/system-error helpers.

Suggested PR Cut

Batch this with related issues in:
node:util: cancellation and structured-clone helper parity

Good batch candidates:

• node:util: expose transferable AbortSignal helpers #3419
• globals: complete AbortSignal static helpers and abort lifecycle #2582

Do not batch with:

• unrelated node:util formatting/debug/system-error helpers
• stream pipeline abort semantics
• broad worker_threads implementation work

Acceptance

• parity/regression test proves util.aborted is a function-valued node:util export
• util.aborted(signal, resource) returns a Promise
• aborting the signal resolves the Promise with the Node-shaped abort event
• implementation matches Node observable behavior
• related known-failure/docs/manifest entries updated if touched