docs: add Arc MCP Server example for Claude Code integration

[consumeobeydie]

Summary

This PR adds an Arc MCP Server example that gives AI tools like Claude Code direct access to Arc Testnet blockchain data.

What's included

• Complete MCP server implementation with 7 blockchain tools
• get_balance, get_transaction, get_block, get_tx_count
• get_agent_info (ERC-8004), get_job_status (ERC-8183), get_network_info
• Claude Code integration instructions

Live Demo

Tested with Claude Code v2.1.169:

• Claude queried Arc Testnet network info in real-time
• Claude fetched ERC-8004 agent data (Agent ID: 69828, Reputation: 95)
• Latest block: 46,336,076

GitHub Repository

https://github.com/consumeobeydie/arc-mcp-server

Related PRs

This completes the full AI developer toolkit for Arc:

1. docs/foundry-smart-contract-deploy-guide
2. docs/x402-arc-agent-example
3. docs/erc8004-agent-registration-example
4. docs/erc8183-job-lifecycle-example
5. docs/unified-agentic-flow-example
6. docs/arc-intelligence-dashboard-example
7. docs/arc-mcp-server-example (this PR)