feat(cohere): add CohereAzureRanker for rerank models served via Azure AI

[Aryan-Pardeshi]

Closes #2795.

Adds a ranker for Cohere rerank models served through Azure AI, in the existing cohere integration rather than a new one — per the conclusion in the issue thread that these models are reached without any Azure SDK dependency.

Built on the reference code @sjrl posted on 2026-04-22, using httpx rather than the Cohere SDK because of cohere-ai/cohere-python#661, which @bglearning flagged on the issue as blocking the SDK route.

Adapted rather than copied — the reference had an import-time os.getenv default, passed a raw Secret through to_dict, defined custom exception classes, and carried a __del__ with a bare except. This follows CohereRanker instead: Secret handling and to_dict/from_dict round-trip, ValueError for validation, and dataclasses.replace so documents are not mutated in place.

Unit tests mock the transport; no credentials or network needed.

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Heads-up for maintainers

This PR is from a fork and touches integrations whose integration tests require API keys.
Those tests are skipped in CI because fork PRs don't have access to repo secrets for security reasons.

Affected integrations:

• cohere

Please run the integration tests locally (hatch run test:integration inside each folder) before approving.

[HaystackBot]

Hi @Aryan-Pardeshi, thanks a lot for your contribution! 🙏

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Coverage report (cohere)

Click to see where and how coverage changed

File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
integrations/cohere/src/haystack_integrations/components/rankers/cohere
azure_ranker.py					116-121, 128
Project Total

This report was generated by python-coverage-comment-action

[bogdankostic]

Thanks a lot for this @Aryan-Pardesh!

I tried the existing CohereRanker against a live Cohere rerank deployment on Azure AI Foundry and it works as-is. I added a working example in #2795. Therefore, I'm closing this PR given that a separate CohereAzureRanker is not needed anyore.

Either way, thanks for the effort you put in here.