Add support for OpenAI image detail parameter, and add support for Anthropic image data URLs

[bcherry]

Two vision-related improvements:

1. Allow the user to override the OpenAI "detail" parameter. While their docs suggest that "auto" is responsive to image sizing, in my testing it appears to not default into "low detail" mode for 512x512 images. Maybe it will for much smaller images? The only way to ensure this uses low detail mode (fixed budget of 85 tokens) is by specifying it.
2. Fill in the missing Anthropic plugin image url support. This one was trickier because Anthropic doesn't support image urls, it only supports base64 images in a special format. Since our ChatImage class doesn't have direct base64 image support, but does support URLs, the straightforward approach solution is to just use data URL anyways and transform it into Anthropic's desired format since it has all the necessary information already. The plugin still throws an error if you pass a non-data-URL (as OpenAI supports remote URLs but Anthropic does not).

Also I improved error messages to be much clearer they're coming from the LiveKit stack and not from the openai or anthropic APIs

[changeset-bot]

🦋 Changeset detected

Latest commit: 483eae1

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
livekit-agents	Patch
livekit-plugins-anthropic	Patch
livekit-plugins-openai	Patch

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[bcherry]

@theomonnom updated to expand the scope, but let me know if you think we should keep iterating on the detail param...

[theomonnom]

Feel free to ignore but if you have time it would be great to add tests for images.
Otherwise lgtm (just fix CI)

[bcherry]

@theomonnom yeah good idea, just added tests!

[theomonnom]

Nice awesome, definitely a great improvement to image handling

[davidzhao]

lgtm! nit on git lfs image

[bcherry]

@theomonnom @nbsp this branch keeps failing CI on seemingly unrelated failures. I've gotten it to pass a couple times by rerunning. is this known in the repo or should I dig into to whether it really is coming from here?

[theomonnom]

yes this is ffmpeg installation on macos failing, feel free to ignore