Missing Azure OpenAI and Ollama providers listed in README

[sridharswain]

Description

The README advertises four pluggable providers:

Pluggable providers -- OpenAI (default), Anthropic, Azure OpenAI, Ollama

However, only the OpenAI provider is implemented (fasteval/providers/openai.py). There is no implementation for:

• Azure OpenAI — no azure_openai.py or similar
• Ollama — no ollama.py or similar

The create_provider_for_model() function in registry.py also only recognizes gpt-*, o1-*, o3-*, and claude-* prefixes.

Suggested Fix

Either:

1. Implement Azure OpenAI and Ollama providers, or
2. Update the README to reflect the currently available providers and add these as a roadmap/future item