feat: Configurable timeout and retry for custom endpoints

[jameslamine]

Summary

This PR adds two new configuration options for custom endpoints:

• timeout: Sets request timeout in milliseconds (default: 10 minutes)
• maxRetries: Sets maximum retry attempts for failed requests (default: 2)

These settings map directly to the OpenAI SDK configuration options and help prevent hanging requests and improve error handling through automatic retries.

Fixes #5567

Example Usage:

endpoints:
  custom:
    - name: "Example"
      timeout: 5000      # 5 second timeout
      maxRetries: 3      # Retry failed requests up to 3 times

Change Type

• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

Testing

1. Configure a custom endpoint with timeout and maxRetries:

endpoints:
  custom:
    - name: "Test Endpoint"
      timeout: 5000
      maxRetries: 3

2. Test scenarios:

• Normal API calls work as expected
• Set a low timeout (1ms) and saw error as expected

Checklist

• I have performed a self-review of my own code
• My changes do not introduce new warnings
• Local unit tests pass with my changes