docs: Document known limitations of Responses

[jwm4]

What does this PR do?

Adds a subpage of the OpenAI compatibility page in the documentation. This subpage documents known limitations of the Responses API.

Closes #3575

[zanetworker]

@jwm4 would we consider prompt-caching a limitation in the API: https://platform.openai.com/docs/api-reference/responses/create#responses-create-prompt_cache_key

Allowing consumers the ability to configure this will matter from a cost/efficiency standpoint (especially with the open implementation here).

[jwm4]

I've addressed the review comments, but I am running out of theories as to how to move forward on getting the CI to pass. Running uv run pre-commit run --all-files and pushing all the changes it makes (to files not involved in this PR) doesn't seem to be getting anywhere. I keep rolling back those commits and trying again, rebasing with main, etc. but it doesn't seem to help.

[ashwinb]

I've addressed the review comments, but I am running out of theories as to how to move forward on getting the CI to pass. Running uv run pre-commit run --all-files and pushing all the changes it makes (to files not involved in this PR) doesn't seem to be getting anywhere. I keep rolling back those commits and trying again, rebasing with main, etc. but it doesn't seem to help.

This is an annoying issue with our pre-commit where we need pre-commit==4.3.0 and python==3.12 and any other combination doesn't make it work. It is likely that one of these is not correct in your environment somehow.

[jwm4]

Thx, @ashwinb ! I had run into similar issues with code change PRs before but I hadn't thought carefully about the implications for documentation PRs. This seems to have sorted out the CI issues. I will open a separate PR to update CONTRIBUTING.md with this info too.