Migrate from raspen prototype to heron live VPS

- Replace raspen references with heron in AGENTS.md
- Update nginx config for live domains (qmoln.se)
- Switch SSL certs to Let's Encrypt paths
- Update WireGuard config with heron's keys and passive listen
- WireGuard direction: agge connects out to heron
- Remove old ssl volume mount, mount /etc/letsencrypt instead

vps/docker-compose.yml

@@ -26,6 +26,6 @@ services:
       - ./nginx/nginx.conf:/etc/nginx/nginx.conf:ro
       - ./nginx/conf.d:/etc/nginx/conf.d:ro
       - ./nginx/stream.d:/etc/nginx/stream.d:ro
-      - ./ssl:/etc/nginx/certs:ro
+      - /etc/letsencrypt:/etc/letsencrypt:ro
       - ./html:/usr/share/nginx/html:ro
     restart: unless-stopped