Add health check endpoint to edge gateway

[dkontango]

Summary

The edge gateway (schmutz) doesn't expose a health check endpoint. Load balancers and orchestrators (Cloudflare, k8s, systemd) need a way to verify the gateway is alive and classifying traffic.

Proposal

Add a lightweight /healthz listener on a separate port (configurable, default 8081). Returns:

{
  "status": "ok",
  "uptime": 3600,
  "connections": 142,
  "hp": 850,
  "version": "1.0.0"
}

Notes

• Must be a separate listener — the main port is raw TLS, not HTTP
• Include HP (Health Points) so monitors can alert on degraded nodes
• Keep it simple — no auth, no middleware