fix(azure): skip /v1 and api-version when baseURL is provided

[Dulani]

Summary

When createAzure({ baseURL: '...' }) is used, the provider currently constructs {baseURL}/v1{path}?api-version=.... This breaks custom API gateways and proxies that handle routing internally and don't expect the /v1 path segment or api-version query parameter.

This PR adds a baseURL branch to the URL construction logic that uses {baseURL}{path} directly — no /v1 appended, no api-version added.

Problem

// Before: baseURL + /v1 + api-version
createAzure({ baseURL: 'https://my-gateway.example.com/azure' })
// → https://my-gateway.example.com/azure/v1/chat/completions?api-version=v1
//                                        ^^^                 ^^^^^^^^^^^^^^
//                                        breaks gateway      breaks gateway

Fix

// After: baseURL used as-is
createAzure({ baseURL: 'https://my-gateway.example.com/azure' })
// → https://my-gateway.example.com/azure/chat/completions

The fix is a 6-line change in the url() function inside createAzure:

  if (options.useDeploymentBasedUrls) {
    fullUrl = new URL(`${baseUrlPrefix}/deployments/${modelId}${path}`);
+ } else if (options.baseURL) {
+   fullUrl = new URL(`${baseUrlPrefix}${path}`);
  } else {
    fullUrl = new URL(`${baseUrlPrefix}/v1${path}`);
  }
- fullUrl.searchParams.set('api-version', apiVersion);
+ if (!options.baseURL) {
+   fullUrl.searchParams.set('api-version', apiVersion);
+ }

Behavior

Configuration	URL constructed
resourceName (default)	https://{name}.openai.azure.com/openai/v1{path}?api-version=v1 ✅ unchanged
useDeploymentBasedUrls: true	{baseURL}/deployments/{id}{path}?api-version=v1 ✅ unchanged
baseURL (new behavior)	{baseURL}{path} — no /v1, no api-version ✅ fixed

Breaking Change

None. The resourceName and useDeploymentBasedUrls paths are unchanged. Only the baseURL path changes, and the previous behavior (appending /v1 and api-version) was undocumented and unintended — the JSDoc said "use a different URL prefix" without mentioning the /v1 suffix.

Tests

Updated 4 existing 'should use the baseURL correctly' tests (responses, chat, image, responses-explicit) to assert the new correct behavior. All 55 tests pass in both node and edge environments.

Related

Closes #13956
Also addresses the api-version issue in #14009 (Foundry project endpoints)

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[Authorship: ~40% AI-assisted, ~60% human review and testing. Tested against a corporate Azure OpenAI gateway at RAND.]

[Dulani]

Thanks for the catch. Fixed in 56942ca — changed the api-version guard from !options.baseURL to !options.baseURL || options.useDeploymentBasedUrls, so deployment-based URLs get api-version even when baseURL is also set. Added a test in 513493b covering the baseURL + useDeploymentBasedUrls combo.