Add healthcheck to Traefik (ping endpoint)

Enable --ping=true and use traefik healthcheck --ping. Lightweight
binary call inside the container, no extra tooling needed.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

traefik/docker-compose.yml

@@ -8,6 +8,7 @@ services:
     command:
       - --api.dashboard=true
       - --api.insecure=false
+      - --ping=true
       - --providers.docker=true
       - --providers.docker.exposedbydefault=false
       - --providers.docker.network=frontend_net
@@ -46,6 +47,12 @@ services:
       - frontend_net
       - backend_net
       - monitoring_net
+    healthcheck:
+      test: ["CMD", "traefik", "healthcheck", "--ping"]
+      interval: 30s
+      timeout: 5s
+      retries: 3
+      start_period: 30s
     labels:
       - traefik.enable=true
       - traefik.docker.network=frontend_net