Add support for Open Responses

[mattt]

https://www.openresponses.org

[Copilot]

Pull request overview

Adds a new OpenResponsesLanguageModel backend to support providers implementing the Open Responses (Responses API–compatible) specification, along with tests and documentation updates.

Changes:

• Introduce OpenResponsesLanguageModel with request/streaming, tools, and structured output support.
• Add Open Responses integration tests and custom generation options tests.
• Document Open Responses support and required test environment variables in the README.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
Sources/AnyLanguageModel/Models/OpenResponsesLanguageModel.swift	New Open Responses-compatible language model implementation (requests, streaming, tools, structured output, custom options).
Tests/AnyLanguageModelTests/OpenResponsesLanguageModelTests.swift	New end-to-end tests (gated by env vars) covering basic, streaming, multimodal, tools, and structured output.
Tests/AnyLanguageModelTests/CustomGenerationOptionsTests.swift	Adds unit tests for OpenResponsesLanguageModel.CustomGenerationOptions (init/equality/codable/integration).
README.md	Documents Open Responses support, usage examples, and test env var requirements.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.