fix(api): document file upload metadata defaults

[jbeckwith-oai]

Summary

Regenerates the Ruby SDK from the latest OpenAPI input and improves upload metadata guidance across generated file parameters.

• Explains that String, StringIO, and pathless IO inputs use generic upload metadata.
• Directs callers to OpenAI::FilePart when they need to override the filename or content type.
• Updates generated model/resource documentation, RBI signatures, the transformed OpenAPI document, and Castiron provenance.

This is documentation-only; runtime behavior and exported type shapes are unchanged.

Source

• Originating API change: openai/openai#1270941
• OpenAPI input: openai/openai-openapi@577fa922

Validation

• Rebased directly onto the current public main
• Every changed file matches the Castiron-generated candidate
• git diff --check
• Thermo-nuclear code-quality review

[HAYDEN-OAI]

Reviewed the generated audio upload metadata documentation and Ruby-specific FilePart guidance against existing multipart behavior. No substantive issues found.

[openai-sdks]

OkTest Summary

✅ 237/237 SDK tests passed in 10.61s for Ruby SDK PR #361.

Test results — 42 files

Test	Result	Time
tests/chat-completions-complex-body.test.ts	✅ Passed	220ms
tests/chat-completions-create.test.ts	✅ Passed	363ms
tests/chat-completions-stream.test.ts	✅ Passed	159ms
tests/files-content-binary.test.ts	✅ Passed	286ms
tests/files-create-multipart.test.ts	✅ Passed	263ms
tests/files-list-pagination.test.ts	✅ Passed	208ms
tests/initialize-config.test.ts	✅ Passed	236ms
tests/instance-isolation.test.ts	✅ Passed	203ms
tests/models-list.test.ts	✅ Passed	308ms
tests/responses-background-lifecycle.test.ts	✅ Passed	345ms
tests/responses-body-method-errors.test.ts	✅ Passed	584ms
tests/responses-cancel-timeout.test.ts	✅ Passed	283ms
tests/responses-cancel.test.ts	✅ Passed	376ms
tests/responses-compact-retries.test.ts	✅ Passed	391ms
tests/responses-compact.test.ts	✅ Passed	341ms
tests/responses-create-advanced-stream.test.ts	✅ Passed	254ms
tests/responses-create-advanced.test.ts	✅ Passed	278ms
tests/responses-create-disconnect.test.ts	✅ Passed	176ms
tests/responses-create-errors.test.ts	✅ Passed	369ms
tests/responses-create-malformed-api-responses.test.ts	✅ Passed	176ms
tests/responses-create-retries.test.ts	✅ Passed	471ms
tests/responses-create-stream-failures.test.ts	✅ Passed	179ms
tests/responses-create-stream-timeout.test.ts	✅ Passed	230ms
tests/responses-create-stream-wire.test.ts	✅ Passed	2.091s
tests/responses-create-stream.test.ts	✅ Passed	131ms
tests/responses-create-terminal-states.test.ts	✅ Passed	442ms
tests/responses-create-timeout.test.ts	✅ Passed	298ms
tests/responses-create.test.ts	✅ Passed	306ms
tests/responses-delete.test.ts	✅ Passed	345ms
tests/responses-input-items-errors.test.ts	✅ Passed	191ms
tests/responses-input-items-list.test.ts	✅ Passed	208ms
tests/responses-input-items-options.test.ts	✅ Passed	226ms
tests/responses-input-tokens-count-timeout.test.ts	✅ Passed	314ms
tests/responses-input-tokens-count.test.ts	✅ Passed	400ms
tests/responses-malformed-inputs.test.ts	✅ Passed	2.283s
tests/responses-not-found-errors.test.ts	✅ Passed	437ms
tests/responses-parse.test.ts	✅ Passed	258ms
tests/responses-retrieve-retries.test.ts	✅ Passed	390ms
tests/responses-retrieve.test.ts	✅ Passed	370ms
tests/responses-stored-method-errors.test.ts	✅ Passed	1.02s
tests/retry-behavior.test.ts	✅ Passed	1.994s
tests/sdk-error-shape.test.ts	✅ Passed	442ms

View OkTest run #31515189704

_{SDK merge (22230e9e89b7) · head (f0cacf37061a) · base (e0a4bc56d528) · OkTest (91635c6a2723)}