docs: add Azure Assistants example

[HAYDEN-OAI]

Summary

• add a runnable examples/azure/assistants.ts program for existing Azure OpenAI Assistants integrations
• configure AzureOpenAI with the resource endpoint and API version, while passing the Azure deployment as the request model
• document why the client-level deployment option is intentionally omitted for resource-scoped Assistants endpoints
• link the example from azure.md with an explicit August 26, 2026 retirement warning

Motivation

Azure Chat Completions requests may be deployment-scoped, but Assistants requests are resource-scoped. The existing examples did not show that distinction, which led users to construct a deployment-scoped base URL that cannot reach Assistants endpoints. This provides a complete example while clearly steering new integrations toward Microsoft Foundry Agents because the legacy Assistants API is deprecated.

Resolves #701

Validation

• pnpm run format
• pnpm exec tsc --noEmit
• pnpm run lint
• git diff --check

[openai-sdks]

OkTest Summary

✅ 237/237 SDK tests passed in 10.537s for Node SDK PR #1975.

Test results — 42 files

Test	Result	Time
tests/chat-completions-complex-body.test.ts	✅ Passed	149ms
tests/chat-completions-create.test.ts	✅ Passed	220ms
tests/chat-completions-stream.test.ts	✅ Passed	185ms
tests/files-content-binary.test.ts	✅ Passed	186ms
tests/files-create-multipart.test.ts	✅ Passed	128ms
tests/files-list-pagination.test.ts	✅ Passed	152ms
tests/initialize-config.test.ts	✅ Passed	209ms
tests/instance-isolation.test.ts	✅ Passed	105ms
tests/models-list.test.ts	✅ Passed	141ms
tests/responses-background-lifecycle.test.ts	✅ Passed	217ms
tests/responses-body-method-errors.test.ts	✅ Passed	365ms
tests/responses-cancel-timeout.test.ts	✅ Passed	232ms
tests/responses-cancel.test.ts	✅ Passed	174ms
tests/responses-compact-retries.test.ts	✅ Passed	249ms
tests/responses-compact.test.ts	✅ Passed	220ms
tests/responses-create-advanced-stream.test.ts	✅ Passed	131ms
tests/responses-create-advanced.test.ts	✅ Passed	174ms
tests/responses-create-disconnect.test.ts	✅ Passed	1.207s
tests/responses-create-errors.test.ts	✅ Passed	212ms
tests/responses-create-malformed-api-responses.test.ts	✅ Passed	162ms
tests/responses-create-retries.test.ts	✅ Passed	293ms
tests/responses-create-stream-failures.test.ts	✅ Passed	215ms
tests/responses-create-stream-timeout.test.ts	✅ Passed	2.17s
tests/responses-create-stream-wire.test.ts	✅ Passed	2.623s
tests/responses-create-stream.test.ts	✅ Passed	106ms
tests/responses-create-terminal-states.test.ts	✅ Passed	210ms
tests/responses-create-timeout.test.ts	✅ Passed	259ms
tests/responses-create.test.ts	✅ Passed	158ms
tests/responses-delete.test.ts	✅ Passed	170ms
tests/responses-input-items-errors.test.ts	✅ Passed	195ms
tests/responses-input-items-list.test.ts	✅ Passed	148ms
tests/responses-input-items-options.test.ts	✅ Passed	210ms
tests/responses-input-tokens-count-timeout.test.ts	✅ Passed	341ms
tests/responses-input-tokens-count.test.ts	✅ Passed	248ms
tests/responses-malformed-inputs.test.ts	✅ Passed	2.242s
tests/responses-not-found-errors.test.ts	✅ Passed	222ms
tests/responses-parse.test.ts	✅ Passed	160ms
tests/responses-retrieve-retries.test.ts	✅ Passed	235ms
tests/responses-retrieve.test.ts	✅ Passed	220ms
tests/responses-stored-method-errors.test.ts	✅ Passed	510ms
tests/retry-behavior.test.ts	✅ Passed	2.993s
tests/sdk-error-shape.test.ts	✅ Passed	285ms

View OkTest run #28820494857

_{SDK merge (8791589d8afd) · head (1f5a15579920) · base (95b54e589491) · OkTest (7fc645091b1a)}