docs: document assistant stream failures

[HAYDEN-OAI]

Summary

• document the Assistants stream abort event alongside error and end
• explain that cancellation through an AbortSignal or .abort() emits abort
• add a safe example that registers both listeners and catches the finalRun() promise

Why

Issue #959 reports unhandled rejections while retrying or cancelling Assistant streams. The current helper already separates API and SDK failures from cancellations, but the Assistants event docs only showed error and did not explain that promise-returning helpers still need their own await or catch.

Impact

Users now have an explicit pattern for handling stream failures before handing a stream to another consumer, including client disconnect and cancellation paths. This clarifies the existing runtime behavior without changing stream semantics.

Validation

• pnpm run format
• pnpm run lint

Resolves #959

[openai-sdks]

OkTest Summary

✅ 237/237 SDK tests passed in 10.845s for Node SDK PR #1979.

Test results — 42 files

Test	Result	Time
tests/chat-completions-complex-body.test.ts	✅ Passed	198ms
tests/chat-completions-create.test.ts	✅ Passed	214ms
tests/chat-completions-stream.test.ts	✅ Passed	213ms
tests/files-content-binary.test.ts	✅ Passed	162ms
tests/files-create-multipart.test.ts	✅ Passed	175ms
tests/files-list-pagination.test.ts	✅ Passed	213ms
tests/initialize-config.test.ts	✅ Passed	174ms
tests/instance-isolation.test.ts	✅ Passed	106ms
tests/models-list.test.ts	✅ Passed	142ms
tests/responses-background-lifecycle.test.ts	✅ Passed	270ms
tests/responses-body-method-errors.test.ts	✅ Passed	329ms
tests/responses-cancel-timeout.test.ts	✅ Passed	209ms
tests/responses-cancel.test.ts	✅ Passed	230ms
tests/responses-compact-retries.test.ts	✅ Passed	294ms
tests/responses-compact.test.ts	✅ Passed	251ms
tests/responses-create-advanced-stream.test.ts	✅ Passed	108ms
tests/responses-create-advanced.test.ts	✅ Passed	237ms
tests/responses-create-disconnect.test.ts	✅ Passed	1.198s
tests/responses-create-errors.test.ts	✅ Passed	215ms
tests/responses-create-malformed-api-responses.test.ts	✅ Passed	151ms
tests/responses-create-retries.test.ts	✅ Passed	237ms
tests/responses-create-stream-failures.test.ts	✅ Passed	292ms
tests/responses-create-stream-timeout.test.ts	✅ Passed	2.193s
tests/responses-create-stream-wire.test.ts	✅ Passed	2.67s
tests/responses-create-stream.test.ts	✅ Passed	81ms
tests/responses-create-terminal-states.test.ts	✅ Passed	217ms
tests/responses-create-timeout.test.ts	✅ Passed	216ms
tests/responses-create.test.ts	✅ Passed	141ms
tests/responses-delete.test.ts	✅ Passed	170ms
tests/responses-input-items-errors.test.ts	✅ Passed	174ms
tests/responses-input-items-list.test.ts	✅ Passed	160ms
tests/responses-input-items-options.test.ts	✅ Passed	280ms
tests/responses-input-tokens-count-timeout.test.ts	✅ Passed	227ms
tests/responses-input-tokens-count.test.ts	✅ Passed	228ms
tests/responses-malformed-inputs.test.ts	✅ Passed	2.329s
tests/responses-not-found-errors.test.ts	✅ Passed	290ms
tests/responses-parse.test.ts	✅ Passed	190ms
tests/responses-retrieve-retries.test.ts	✅ Passed	235ms
tests/responses-retrieve.test.ts	✅ Passed	333ms
tests/responses-stored-method-errors.test.ts	✅ Passed	577ms
tests/retry-behavior.test.ts	✅ Passed	3.088s
tests/sdk-error-shape.test.ts	✅ Passed	268ms

View OkTest run #28824774087

_{SDK merge (2ad625900c9b) · head (48f787a31acb) · base (95b54e589491) · OkTest (7fc645091b1a)}