Add direct host/base_url support for Azure OpenAI

[TonsOfFun]

Summary

• Adds support for configuring Azure OpenAI with a direct host or base_url parameter
• Makes azure_resource and deployment_id optional when host is provided
• Supports Azure AI Foundry endpoints (cognitiveservices.azure.com), custom domains, and any Azure OpenAI-compatible endpoint

Motivation

The current Azure configuration requires azure_resource and deployment_id which constructs the URL as:

https://{azure_resource}.openai.azure.com/openai/deployments/{deployment_id}

However, many Azure deployments use different URL patterns:

• Azure AI Foundry: https://{resource}.cognitiveservices.azure.com/openai/deployments/{model}
• Custom domains
• Regional endpoints

This change allows direct URL configuration:

azure:
  service: "AzureOpenAI"
  api_key: <%= ENV["AZURE_OPENAI_API_KEY"] %>
  host: "https://mycompany.cognitiveservices.azure.com/openai/deployments/gpt-4"
  api_version: "2024-10-21"

Test plan

• New tests added for direct host configuration
• Existing tests continue to pass
• Manual testing with Azure AI Foundry endpoint

🤖 Generated with Claude Code