[Backend] Platform Health Metrics API

[Olowodarey]

📋 Description

Create public endpoint showing platform health metrics and transparency data.

Acceptance Criteria

• GET /analytics/platform/health (public endpoint)
• Show total value locked (TVL)
• Number of active users and savings accounts
• Average APY across products
• Total interest distributed
• Platform uptime percentage
• Smart contract audit status
• Cache with 15-minute TTL

Response Example

{
  totalValueLocked: 12500000.50,
  activeUsers: 8932,
  activeSavingsAccounts: 15420,
  averageAPY: 8.5,
  totalInterestDistributed: 450000.75,
  platformUptime: 99.98,
  lastAuditDate: "2026-01-15"
}

Tasks

• Create platform health endpoint
• Implement metrics calculation
• Add caching
• Make endpoint public
• Write tests