Add support for Azure-hosted Mistral OCR #122

Problem

The @mistralai/mistralai-azure doesn't support Mistral OCR, forcing developers to bypass the SDK entirely.

• OCR models are not accessible through the SDK
• Developers must use manual HTTP POST requests to the endpoint
• No type definitions exist for OCR response objects -> No way to properly parse or validate OCR API responses

Expected Behaviour

• OCR models should be accessible through the SDK's standard interface
• Type definitions for OCR requests and responses
• Proper error handling and response parsing

Impact

• Loss of type safety when working with OCR on Azure
• Inconsistent developer experience compared to other model types (and providers)
• Increased boilerplate code for OCR integration