feat(azure): update default provider to use responses API

[rahulbhadja]

Background

• Azure OpenAI defaulted to the chat endpoint, but 📯 Azure community team updates #9863 discussed responses to be the default to match current guidance.

Summary

• Make the main azure() factory and languageModel alias invoke the Responses API by default.
• Update the Azure provider tests to cover the new default responses flow..
• Add an example src/generate-text/azure-responses-default.ts that demonstrates the default responses usage.
• add note in Azure OpenAI provider docs about the new default.

Manual Verification

• ran example examples/ai-core/src/generate-text/azure-responses-default.ts

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)

Future Work

N/A

Related Issues

Fixes #8596 and #9890

[rahulbhadja]

hi @gr2m , addressed the issue from the Azure community discussion. Let me know if any changes are needed. Thanks

[tsuzaki430]

@rahulbhadja

Hello.
Thank you for creating this pull request. I tested it by actually touching it and found no issues.
There is currently a conflict, but I think we can proceed with merging once it is resolved🚀

[rahulbhadja]

@rahulbhadja

Hello. Thank you for creating this pull request. I tested it by actually touching it and found no issues. There is currently a conflict, but I think we can proceed with merging once it is resolved🚀

thanks @tsuzaki430 for your review, once @gr2m gives greenlight we can solve confilicts

[gr2m]

Looks great, thank you @rahulbhadja for putting it together and thank you @tsuzaki430 for testing!