docs: Add OpenRouter integration documentation

Author: yassais

docs/openrouter.md

@@ -0,0 +1,93 @@
+# Using Lyra Web3 Playground with OpenRouter
+
+Lyra Web3 Playground is an interactive platform for experimenting with Web3 technologies, smart contracts, and AI-assisted development. It supports OpenRouter for AI-powered features.
+
+## What is OpenRouter?
+
+[OpenRouter](https://openrouter.ai) provides access to 200+ AI models through a unified API.
+
+## Setup
+
+### 1. Get Your OpenRouter API Key
+
+1. Sign up at [openrouter.ai](https://openrouter.ai)
+2. Generate an API key at [openrouter.ai/settings/keys](https://openrouter.ai/settings/keys)
+
+### 2. Configure Environment
+
+```bash
+# Server-side
+export OPENROUTER_API_KEY=sk-or-v1-your-key-here
+export OPENROUTER_MODEL=anthropic/claude-sonnet-4
+
+# Client-side (Vite)
+VITE_OPENROUTER_API_KEY=sk-or-v1-your-key-here
+```
+
+### 3. Run
+
+```bash
+npm install
+npm run dev
+```
+
+## AI Features
+
+With OpenRouter configured:
+
+| Feature | Description |
+|---------|-------------|
+| **Contract Generation** | AI-generated Solidity contracts |
+| **Code Explanation** | Understand smart contract code |
+| **Test Generation** | Auto-generate contract tests |
+| **Security Analysis** | AI-powered vulnerability detection |
+
+## Example Usage
+
+### Generate a Smart Contract
+
+```
+Prompt: "Create an ERC-20 token with minting and burning"
+```
+
+The AI will generate a complete, audited Solidity contract using your chosen OpenRouter model.
+
+### Explain Code
+
+```
+Prompt: "Explain what this reentrancy guard does"
+```
+
+Get detailed explanations of any smart contract code.
+
+## Provider Priority
+
+```
+OpenRouter → OpenAI
+```
+
+When `OPENROUTER_API_KEY` is set, it takes priority over direct OpenAI.
+
+## Recommended Models
+
+| Model | Use Case |
+|-------|----------|
+| `anthropic/claude-sonnet-4` | Complex contracts |
+| `openai/gpt-4o` | General development |
+| `deepseek/deepseek-coder` | Code-focused tasks |
+
+## Self-Hosting
+
+```bash
+git clone https://github.com/nirholas/lyra-web3-playground
+cd lyra-web3-playground
+npm install
+echo "OPENROUTER_API_KEY=sk-or-v1-..." > .env
+npm run build && npm start
+```
+
+## Resources
+
+- [GitHub](https://github.com/nirholas/lyra-web3-playground)
+- [Live Demo](https://playground.lyra.finance)
+- [OpenRouter Docs](https://openrouter.ai/docs)