feat: Implement SmartRouter (Unified API, Fallback, Load Balancing)

[daiquydev]

Overview

This PR implements a SmartRouter for the JS SDK, inspired by LiteLLM in Python, as requested in issue #286.

Key Features

• Unified API: Standardizes request and response formats across different providers (OpenAI, Gemini, Llama) using an OpenAI-compatible interface.
• • Routing Strategies:

• - **Fallback**: Automatically switches to the next available provider if the primary one fails.
  

• - **Load Balancing**: Distributes requests across multiple providers using weighted random selection.
  

• • Provider Support: Initial support for OpenAI, Gemini, and Llama.
• • Easy Integration: Fully integrated into the @arakoodev/edgechains.js/ai module.
• • Example: Added a standalone example in examples/smart-router to demonstrate usage.

Technical Details

• Created a new router module within the AI package.
• • Implemented mapping logic to translate provider-specific responses into a unified UnifiedChatResponse format.
• • Merged and standardized types for messages and options.
    Closes BOUNTY: Convert the endpoints to a smart router like litellm does in python #286

[github-actions]

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[daiquydev]

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[daiquydev]

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