fix(audio): preserve recording outcomes during cancellation and cleanup (#2482)

## Summary

- Preserve the first recording result when caller/timeout abort
listeners, output-stream cleanup, logging sinks, or subprocess
cancellation callbacks throw or reenter.
- Reliably observe caller and timeout cancellation during listener
registration while preserving listener ownership, intentional-stop
semantics, and captured-audio privacy.
- Add 37 regression tests through the documented `openai/helpers/audio`
public entrypoint, including independent cleanup failures, late private
output, cross-signal races, and native subprocess failure modes.

## Validation

- Node.js 22.23.0 and 26.7.0: 6,566 handwritten tests plus 556 generated
tests pass on each runtime.
- Canonical lint, strict TypeScript, production build, published-source
TypeScript 4.9 and 6, and package lint.
- Packed CommonJS/ESM package validation on both runtimes, including
actual public audio-helper cancellation regressions.