CLI cannot connect to Azure AI Foundry Serverless endpoints or OpenAI-compatible APIs

Describe the bug

The CLI (v1.1.51) currently cannot connect to Azure AI Foundry Serverless endpoints or other OpenAI-compatible APIs (like vLLM) because of two restrictive design choices:

1. Azure Provider: Forces a resourceName and builds a legacy URL path (/openai/deployments/...), which results in Resource not found for Serverless endpoints.
2. OpenAI Provider: Validates the model name against a hardcoded internal list, rejecting any non-standard model names (like DeepSeek-V3.2) even when a custom baseURL is defined.

Steps to Reproduce

Setup: Azure AI Foundry Serverless Deployment (DeepSeek-V3.2)
Endpoint: https://<id>.services.ai.azure.com/openai/v1

Attempt 1: Using azure provider

{
  "model": "azure/deepseek-v3.2",
  "provider": {
    "azure": {
      "options": {
        "apiKey": "REDACTED",
        "baseURL": "https://<id>.services.ai.azure.com/openai/v1"
      }
    }
  }
}

Error: AI_LoadSettingError: Azure OpenAI resource name setting is missing.

Conflict: Serverless endpoints do not follow the {resourceName}.openai.azure.com pattern. Adding a dummy resourceName causes the CLI to construct an invalid URL.

Attempt 2: Using openai provider (as a proxy)

{
  "model": "openai/DeepSeek-V3.2",
  "provider": {
    "openai": {
      "options": {
        "apiKey": "REDACTED",
        "baseURL": "https://<id>.services.ai.azure.com/openai/v1"
      }
    }
  }
}

Error: ProviderModelNotFoundError (model name is not in the hardcoded list for OpenAI).

Expected Behavior

• BaseURL Priority: If a baseURL is provided, the CLI should respect it as a full path and stop appending provider-specific path segments (like /deployments/).
• Flexible Validation: Disable model name validation when a custom baseURL is present to support the growing ecosystem of OpenAI-compatible providers (Foundry, vLLM, Ollama).
• Optional resourceName: Make resourceName optional for the Azure provider when using Foundry Serverless URLs.

Environment

• OS: Windows 11
• OpenCode Version: 1.1.51
• Model: DeepSeek-V3.2 via Azure AI Foundry Serverless

Additional Context

Azure AI Foundry Serverless endpoints use a different URL structure than traditional Azure OpenAI deployments. The current implementation assumes all Azure endpoints follow the legacy pattern, which breaks compatibility with newer Azure AI services.