The xAI /v1/responses API returns content in a structured format with
typed output blocks (type: 'message') containing typed content blocks
(type: 'output_text') and url_citation annotations. The previous code
only checked output[0].content[0].text without filtering by type,
which could miss content in responses with multiple output entries.
Changes:
- Update GrokSearchResponse type to include annotations on content blocks
- Filter output blocks by type='message' and content by type='output_text'
- Extract url_citation annotations as fallback citations when top-level
citations array is empty
- Deduplicate annotation-derived citation URLs
- Update tests for the new structured return type
Closes#13520
27453f5a31