fix(provider/xai): streamText delta validation error with xAI x_search tool

[syeddhasnainn]

Background

streamText was throwing a validation error when using the x_search tool because some event types returned by xAI were missing from the xaiResponsesChunkSchema

Summary

I updated the chunkSchema with the missing types and also added a test in packages/xai/src/responses/xai-responses-language-model.test.ts

Manual Verification

I tested it by running the xai-x-search-video-understanding example

Checklist

• Tests have been added / updated (for bug fixes / features)
• Documentation has been added / updated (for bug fixes / features)
• A patch changeset for relevant packages has been added (for bug fixes / features - run pnpm changeset in the project root)
• I have reviewed this pull request (self-review)

Related Issues

fixes #10628

[syjcnss]

@syeddhasnainn This fix missed the delta field in custom_tool_call_input.delta and the input filed in custom_tool_call_input.done. My PR addresses the same problem #10715 . You may want to add them and I'm closing my PR.

[syeddhasnainn]

Can you please recheck? I can see both the events.

[syjcnss]

Rechecked. I can confirm the event stream works without defining the delta and input fields. Nice work.