fix: avoid deep Deno Zod types

[HAYDEN-OAI]

Summary

• narrow the public zodResponseFormat() generic constraint to the small Zod surface the helper actually needs
• infer parsed output directly from the schema _output type
• keep the existing Zod v3/v4 runtime schema conversion unchanged
• add coverage that the returned parser still preserves inferred output types

Why

Issue #984 reports that deno check can fail with TS2589 or exhaust the JavaScript heap when calling zodResponseFormat(). The previous public signature asked Deno to structurally compare the supplied schema against the complete Zod v3 and v4 type graphs before inferring the output type.

Impact

Deno no longer needs to expand those full Zod graphs at the call site. The helper still accepts Zod v3 and v4 schemas, produces the same JSON Schema at runtime, and preserves the inferred parsed result through _output.

Validation

• reproduced the Deno 2.9.0 heap exhaustion before the change and verified the same call no longer enters the OOM path afterward
• pnpm exec jest tests/helpers/zod.test.ts --runInBand
• pnpm exec tsc --noEmit
• pnpm run lint

Resolves #984

[openai-sdks]

OkTest Summary

✅ 237/237 SDK tests passed in 11.226s for Node SDK PR #1980.

Test results — 42 files

Test	Result	Time
tests/chat-completions-complex-body.test.ts	✅ Passed	262ms
tests/chat-completions-create.test.ts	✅ Passed	262ms
tests/chat-completions-stream.test.ts	✅ Passed	267ms
tests/files-content-binary.test.ts	✅ Passed	195ms
tests/files-create-multipart.test.ts	✅ Passed	258ms
tests/files-list-pagination.test.ts	✅ Passed	309ms
tests/initialize-config.test.ts	✅ Passed	164ms
tests/instance-isolation.test.ts	✅ Passed	132ms
tests/models-list.test.ts	✅ Passed	195ms
tests/responses-background-lifecycle.test.ts	✅ Passed	193ms
tests/responses-body-method-errors.test.ts	✅ Passed	307ms
tests/responses-cancel-timeout.test.ts	✅ Passed	197ms
tests/responses-cancel.test.ts	✅ Passed	196ms
tests/responses-compact-retries.test.ts	✅ Passed	253ms
tests/responses-compact.test.ts	✅ Passed	229ms
tests/responses-create-advanced-stream.test.ts	✅ Passed	163ms
tests/responses-create-advanced.test.ts	✅ Passed	172ms
tests/responses-create-disconnect.test.ts	✅ Passed	1.207s
tests/responses-create-errors.test.ts	✅ Passed	189ms
tests/responses-create-malformed-api-responses.test.ts	✅ Passed	179ms
tests/responses-create-retries.test.ts	✅ Passed	288ms
tests/responses-create-stream-failures.test.ts	✅ Passed	252ms
tests/responses-create-stream-timeout.test.ts	✅ Passed	2.259s
tests/responses-create-stream-wire.test.ts	✅ Passed	2.683s
tests/responses-create-stream.test.ts	✅ Passed	92ms
tests/responses-create-terminal-states.test.ts	✅ Passed	207ms
tests/responses-create-timeout.test.ts	✅ Passed	210ms
tests/responses-create.test.ts	✅ Passed	274ms
tests/responses-delete.test.ts	✅ Passed	227ms
tests/responses-input-items-errors.test.ts	✅ Passed	363ms
tests/responses-input-items-list.test.ts	✅ Passed	219ms
tests/responses-input-items-options.test.ts	✅ Passed	196ms
tests/responses-input-tokens-count-timeout.test.ts	✅ Passed	225ms
tests/responses-input-tokens-count.test.ts	✅ Passed	232ms
tests/responses-malformed-inputs.test.ts	✅ Passed	2.438s
tests/responses-not-found-errors.test.ts	✅ Passed	251ms
tests/responses-parse.test.ts	✅ Passed	182ms
tests/responses-retrieve-retries.test.ts	✅ Passed	262ms
tests/responses-retrieve.test.ts	✅ Passed	237ms
tests/responses-stored-method-errors.test.ts	✅ Passed	599ms
tests/retry-behavior.test.ts	✅ Passed	3.126s
tests/sdk-error-shape.test.ts	✅ Passed	292ms

View OkTest run #28825739887

_{SDK merge (71f3c7c1fae5) · head (2f8e7ef19a4f) · base (95b54e589491) · OkTest (7fc645091b1a)}