Add service health monitoring indicators

[Awaiswilll]

Description

Add health check indicators to the Dashboard that show whether each service is responding correctly, not just whether it's running.

What Needs to Be Done

• Add health check endpoint to services
• Display health status (healthy/degraded/unhealthy) on Dashboard
• Add color-coded indicators (green/yellow/red)
• Show last health check timestamp

Acceptance Criteria

• Each service shows health status on Dashboard
• Health checks run every 30 seconds
• Status updates in real-time without page refresh
• Degraded services show warning icon

Relevant Files

• src/views/Dashboard.tsx — Service cards
• tools/dweb-server.cjs — Health check endpoint
• src/types.ts — Service type definition