RPC Health Monitor CLI

Description

Create a lightweight CLI tool that continuously monitors the health of RPC endpoints used by the RWA.io ecosystem. It should track response latency, block height sync status, and error rates for Ethereum, Polygon, and Avalanche endpoints. Output should be structured JSON suitable for dashboards and alerting pipelines.

Requirements

• Node.js CLI with configurable endpoint list
• Measure latency, block height, and error rate
• JSON output for each health check cycle
• Configurable polling interval

Acceptance Criteria

• Runs against at least 3 RPC endpoints
• Outputs valid JSON to stdout
• Handles endpoint failures gracefully
• README with usage examples