feat: add SmartRouter for unified LLM routing

[tarai-dl]

Summary

Adds a SmartRouter class that works like LiteLLM - pass any model name and it auto-routes to the correct provider.

Features:

• Auto-detection: Model name prefix determines provider (gpt-* → OpenAI, gemini-* → Gemini, llama-* → Llama)
• Fallback chain: If primary provider fails, tries next provider in priority order
• Extensible: Register custom providers via config
• Unified API: Single router.chat({ model, prompt }) call regardless of backend
• Utilities: listProviders(), isModelSupported(), detectProvider()

Provider Patterns:

Provider	Model Patterns
OpenAI	gpt-, o1-, o3-, chatgpt-, text-embedding-, dall-e-
Gemini	gemini-, palm-, bison-*
Llama	llama-, meta-llama/, mixtral-, mistral-, qwen-, deepseek-

Usage:

import { SmartRouter } from "@arakoodev/edgechains";

const router = new SmartRouter({
    openaiApiKey: process.env.OPENAI_API_KEY,
    geminiApiKey: process.env.GEMINI_API_KEY,
});

// Auto-routes to correct provider based on model name
const response = await router.chat({
    model: "gpt-4o",
    prompt: "Hello!",
});
// response = { content: "...", provider: "openai", model: "gpt-4o" }

// Fallback: if OpenAI fails, tries Gemini
const response2 = await router.chat({
    model: "gpt-4o",
    prompt: "Hello!",
});
// Falls back to Gemini if OpenAI errors

Files Added:

• JS/edgechains/arakoodev/src/ai/src/lib/smart-router/smartRouter.ts
• JS/edgechains/arakoodev/src/ai/src/tests/smart-router.test.ts

Files Modified:

• JS/edgechains/arakoodev/src/ai/src/index.ts — added SmartRouter export

Closes #286

/claim #286

[github-actions]

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[tarai-dl]

I have read the Arakoo CLA Document and I hereby sign the CLA