feat: rerank support extra headers

[caisirius]

Description

Add extra_headers configuration support to the rerank functionality. This enables users to use rerank services through API gateways that require custom HTTP headers (e.g., x-gw-apikey for authentication). The implementation follows the same pattern as the existing extra_headers support in embedding and VLM configurations.

Related Issue

Fixes #1314

Type of Change

• New feature (non-breaking change that adds functionality)

Changes Made

• Added extra_headers: Optional[Dict[str, str]] field to RerankConfig
• Modified OpenAIRerankClient.__init__ to accept and store extra_headers
• Updated OpenAIRerankClient.from_config to extract extra_headers from config
• Modified OpenAIRerankClient.rerank_batch to merge extra_headers into API request headers
• Added comprehensive test coverage (10 tests)

Testing

• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
  • All 10 new tests pass (3 config tests + 7 client tests)
  • No regressions in existing rerank tests
• I have tested this on the following platforms:
  • Linux
  • macOS
  • Windows

Checklist

• My code follows the project's coding style
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published

Additional Notes

The implementation allows users to configure custom headers like:

{
  "rerank": {
    "api_base": "https://gateway.com/v1/rerank",
    "api_key": "internal-key",
    "extra_headers": {"x-gw-apikey": "Bearer real-key"}
  }
}

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[github-actions]

PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

🎫 Ticket compliance analysis ✅ 1314 - Fully compliant Compliant requirements: Added extra_headers field to RerankConfig Modified OpenAIRerankClient to accept and merge extra headers Updated from_config to extract extra headers from config Added comprehensive test coverage Updated both English and Chinese documentation

⏱️ Estimated effort to review: 2 🔵🔵⚪⚪⚪

🏅 Score: 95

🧪 PR contains tests

🔒 No security concerns identified

✅ No TODO sections

🔀 No multiple PR themes

⚡ No major issues detected

[github-actions]

PR Code Suggestions ✨

No code suggestions found for the PR.